Cross flow manifold for electroplating apparatus

ABSTRACT

The embodiments herein relate to methods and apparatus for electroplating one or more materials onto a substrate. In many cases the material is a metal and the substrate is a semiconductor wafer, though the embodiments are no so limited. Typically, the embodiments herein utilize a channeled plate positioned near the substrate, creating a cross flow manifold defined on the bottom by the channeled plate, on the top by the substrate, and on the sides by a cross flow confinement ring. During plating, fluid enters the cross flow manifold both upward through the channels in the channeled plate, and laterally through a cross flow side inlet positioned on one side of the cross flow confinement ring. The flow paths combine in the cross flow manifold and exit at the cross flow exit, which is positioned opposite the cross flow inlet. These combined flow paths result in improved plating uniformity.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 13/172,642, [attorney docket NOVLP367] filed Jun. 29, 2011, andtitled “CONTROL OF ELECTROLYTE HYDRODYNAMICS FOR EFFICIENT MASS TRANSFERDURING ELECTROPLATING,” which claims benefit of prior to U.S.Provisional Application Nos. 61/405,608, [attorney docket NOVLP396P]filed Oct. 21, 2010, and titled “FLOW DIVERTERS AND FLOW SHAPING PLATESFOR ELECTROPLATING CELLS;” 61/374,911, [attorney docket NOVLP367P] filedAug. 18, 2010, and titled “HIGH FLOW RATE PROCESSING FOR WAFER LEVELPACKAGING;” and 61/361,333, [attorney docket NOVLP366P] filed Jul. 2,2010, and titled “ANGLED HRVA,” each of which is incorporated byreference herein in its entirety and for all purposes. Further, thisapplication claims benefit of prior to U.S. Provisional Application Nos.61/646,598, [attorney docket NOVLP367X1P] filed May 14, 2012, and titled“CROSS FLOW MANIFOLD FOR ELECTROPLATING APPARATUS;” and 61/736,499[attorney docket LAMRP015P] filed Dec. 12, 2012, and titled “ENHANCEMENTOF ELECTROLYTE HYDRODYNAMICS FOR EFFICIENT MASS TRANSFER DURINGELECTROPLATING,” each of which is incorporated herein in its entiretyand for all purposes.

BACKGROUND

The disclosed embodiments relate to methods and apparatus forcontrolling electrolyte hydrodynamics during electroplating. Moreparticularly, methods and apparatus described herein are particularlyuseful for plating metals onto semiconductor wafer substrates, such asthrough resist plating of small microbumping features (e.g., copper,nickel, tin and tin alloy solders) having widths less than, e.g., about50 μm, and copper through silicon via (TSV) features.

Electrochemical deposition processes are well-established in modernintegrated circuit fabrication. The transition from aluminum to coppermetal line interconnections in the early years of the twenty-firstcentury drove a need for increasingly sophisticated electrodepositionprocesses and plating tools. Much of the sophistication evolved inresponse to the need for ever smaller current carrying lines in devicemetallization layers. These copper lines are formed by electroplatingthe metal into very thin, high-aspect ratio trenches and vias in amethodology commonly referred to as “damascene” processing(pre-passivation metalization).

Electrochemical deposition is now poised to fill a commercial need forsophisticated packaging and multichip interconnection technologies knowngenerally and colloquially as wafer level packaging (WLP) and throughsilicon via (TSV) electrical connection technology. These technologiespresent their own very significant challenges due in part to thegenerally larger feature sizes (compared to Front End of Line (FEOL)interconnects) and high aspect ratios.

Depending on the type and application of the packaging features (e.g.,through chip connecting TSV, interconnection redistribution wiring, orchip to board or chip bonding, such as flip-chip pillars), platedfeatures are usually, in current technology, greater than about 2micrometers and are typically about 5-100 micrometers in their principaldimension (for example, copper pillars may be about 50 micrometers). Forsome on-chip structures such as power busses, the feature to be platedmay be larger than 100 micrometers. The aspect ratios of the WLPfeatures are typically about 1:1 (height to width) or lower, though theycan range as high as perhaps about 2:1 or so, while TSV structures canhave very high aspect ratios (e.g., in the neighborhood of about 20:1).

With the shrinking of WLP structure sizes from 100-200 um to less than50 um comes a unique set of problems because at this scale, thehydrodynamic and mass transfer boundary layers are nearly equivalent.For prior generations with larger features, the transport of fluid andmass into a feature was carried by the general penetration of the flowfields into the features, but with smaller features, the formation offlow eddies and stagnation can inhibit both the rate and uniformity ofmass transport within the growing feature. Therefore, new methods ofcreating uniform mass transfer within smaller “microbump” and TSVfeatures are required.

Further, the time constant τ (the 1D diffusion equilibration timeconstant) for a purely diffusion process scales with feature depth L andthe diffusion constant D as

$\tau = {\frac{L^{2}}{2\; D}{\left( \sec \right).}}$

Assuming an average-reasonable value for the diffusion coefficient of ametal ion (e.g., 5×10⁻⁶ cm²/sec), a relatively large FEOL 0.3 um deepdamascene feature would have a time constant of only about 0.1 msec, buta 50 um deep TSV of WLP bump would have a time constant of severalseconds.

Not only feature size, but also plating speed differentiates WLP and TSVapplications from damascene applications. For many WLP applications,depending on the metal being plated (e.g., copper, nickel, gold, silversolders, etc.), there is a balance between the manufacturing and costrequirements on the one hand and the technical requirements andtechnical difficulty on the other hand (e.g., goals of capitalproductivity with wafer pattern variability and on wafer requirementslike within die and within feature targets). For copper, this balance isusually achieved at a rate of at least about 2 micrometers/minute, andtypically at least about 3-4 micrometers/minute or more. For tinplating, a plating rate of greater than about 3 um/min, and for someapplications at least about 7 micrometers/minute may be required. Fornickel and strike gold (e.g., low concentration gold flash film layers),the plating rates may be between about 0.1 to 1 um/min. At thesemetal-relative higher plating rate regimes, efficient mass transfer ofmetal ions in the electrolyte to the plating surface is important.

In certain embodiments, plating must be conducted in a highly uniformmanner over the entire face of a wafer to achieve good platinguniformity WIthin a Wafer (WIW), WIthin and among all the features of aparticular Die (WID), and also WIthin the individual Features themselves(WIF). The high plating rates of WLP and TSV applications presentchallenges with respect to uniformity of the electrodeposited layer. Forvarious WLP applications, plating must exhibit at most about 5% halfrange variation radially along the wafer surface (referred to as WIWnon-uniformity, measured on a single feature type in a die at multiplelocations across the wafer's diameter). A similar equally challengingrequirement is the uniform deposition (thickness and shape) of variousfeatures of either different sizes (e.g. feature diameters) or featuredensity (e.g. an isolated or embedded feature in the middle of an arrayof the chip die). This performance specification is generally referredto as the WID non-uniformity. WID non-uniformity is measured as thelocal variability (e.g. <5% half range) of the various features types asdescribed above versus the average feature height or other dimensionwithin a given wafer die at that particular die location on the wafer(e.g. at the mid radius, center or edge).

A final challenging requirement is the general control of the withinfeature shape. Without proper flow and mass transfer convection control,after plating a line or pillar can end up being sloped in either aconvex, flat or concave fashion in two or three dimensions (e.g. asaddle or a domed shape), with a flat profile generally, though notalways, preferred. While meeting these challenges, WLP applications mustcompete with conventional, potentially less expensive pick and placeserial routing operations. Still further, electrochemical deposition forWLP applications may involve plating various non-copper metals such assolders like lead, tin, tin-silver, and other underbump metallizationmaterials, such as nickel, gold, palladium, and various alloys of these,some of which include copper. Plating of tin-silver near eutectic alloysis an example of a plating technique for an alloy that is plated as alead free solder alternative to lead-tin eutectic solder.

SUMMARY

Certain embodiments herein relate to methods and apparatus forelectroplating one or more materials onto a substrate. In many cases thematerial is a metal and the substrate is a semiconductor wafer, thoughthe embodiments are no so limited. Typically, the embodiments hereinutilize a channeled plate positioned near the substrate, creating across flow manifold defined on the bottom by the channeled plate, on thetop by the substrate, and on the sides by a cross flow confinement ring.During plating, fluid enters the cross flow manifold both upward throughthe channels in the channeled plate, and laterally through a cross flowside inlet positioned on one side of the cross flow confinement ring.The flow paths combine in the cross flow manifold and exit at the crossflow exit, which is positioned opposite the cross flow inlet. Thesecombined flow paths result in improved plating uniformity.

In one aspect of the embodiments herein, an apparatus is provided.including (a) an electroplating chamber configured to contain anelectrolyte and an anode while electroplating metal onto a substantiallyplanar substrate, (b) a substrate holder configured to hold asubstantially planar substrate such that a plating face of the substrateis separated from the anode during electroplating, (c) an ionicallyresistive element including a substrate-facing surface that is separatedfrom the plating face of the substrate by a gap of about 10 mm or less,where the ionically resistive element is at least coextensive with theplating face of the substrate during electroplating, and where theionically resistive element is adapted to provide ionic transportthrough the element during electroplating, (d) an inlet to the gap forintroducing electrolyte to the gap, and (e) an outlet to the gap forreceiving electrolyte flowing in the gap, where the inlet and outlet arepositioned proximate azimuthally opposing perimeter locations on theplating face of the substrate during electroplating, and where the inletand outlet are adapted to generate cross-flowing electrolyte in the gapto create or maintain a shearing force on the plating face of thesubstrate during electroplating. In some implementations, the inlet ofthe apparatus is separated into two or more azimuthally distinctsections, and the apparatus also includes a mechanism for independentlycontrolling the amount of electrolyte flowing to the azimuthallydistinct sections of the inlet.

In certain embodiments, the ionically resistive element has certainproperties. For example, in some cases, the ionically resistive elementhas a porosity of between about 1-10% (e.g., between about 2-5%). Theionically resistive element may also include at least about 1,000 (e.g.,at least about 3,000, at least about 5,000, at least about 6,000, or atleast about 9,000) paths through which electrolyte may flow duringelectroplating. The paths may be configured to deliver electrolytetowards the substrate at a velocity of at least about 3 cm/s (e.g., atleast about 5 cm/s, or at least about 10 cm/s) at the outlets of thepaths through the ionically resistive element. In many cases theionically resistive element is configured to shape an electric field andcontrol electrolyte flow characteristics proximate the substrate duringelectroplating.

The apparatus may also include a lower manifold region positioned belowa lower face of the ionically resistive element, where the lower facefaces away from the substrate holder. In some embodiments, the apparatusincludes a central electrolyte chamber and one or more feed channelsconfigured to delivery electrolyte from the central electrolyte chamberto both the inlet and to the lower manifold region. A pump may be usedin various cases for delivering electrolyte to and/or from the centralelectrolyte chamber. In some embodiments, the pump and inlet are adaptedto deliver electrolyte in the gap at a cross flow velocity of at leastabout 3 cm/s (e.g., at least about 5 cm/s, or at least about 10 cm/s, orat least about 15 cm/s, or at least about 20 cm/s) across a center pointon the plating face of the substrate.

In various implementations, the apparatus includes a cross flowinjection manifold that is fluidically coupled to the inlet. The crossflow injection manifold may be at least partially defined by a cavity inthe ionically resistive element. Flow directing elements may bepositioned in the gap in certain embodiments, and the flow directingelements may be adapted to cause electrolyte to flow in a substantiallylinear flow path from the inlet to the outlet. In some cases the flowdirecting elements are partitions/fins located downstream from the inletand configured to divide flowing electrolyte into adjacent streams inthe gap.

Certain embodiments include a flow confinement ring, which may bepositioned over a peripheral portion of the ionically resistive element.The flow confinement ring helps shape the cross flow across the face ofthe substrate. In cases where a cross flow confinement ring is used, agasket may be positioned between the ionically resistive element and theflow confinement ring. The gasket helps provide a good seal. A membraneframe may be used in various embodiments to support a membrane. Themembrane may separate the electroplating chamber into a cathode chamberand an anode chamber. In various implementations, a weir wall ispositioned radially outside the gap, and is configured to receiveelectrolyte flowing through the outlet. The apparatus may also include amechanism for rotating the substrate and/or substrate holder duringplating. In some cases, the ionically resistive element is positionedparallel or substantially parallel to the substrate duringelectroplating.

The inlet may span an arc proximate the perimeter of the plating face ofthe substrate in various embodiments. In some implementations, the inletspans an arc between about 90-180° (e.g., between about 120-170°,between about)140-150°. In a particular embodiment, the inlet spans anarc of about 90°. In another embodiment, the inlet spans an arc of about120°. In some embodiments, the inlet is separated into a plurality ofazimuthally distinct segments. These azimuthally distinct segments mayalso be fluidically separated. The azimuthally distinct segments of theinlets may be fed by a plurality of electrolyte feeds and feed inlets.In some implementations, the apparatus may include one or more flowcontrol elements that are designed or configured to independentlycontrol the volumetric flow rates of electrolyte to the differentelectrolyte feed inlets. The flow control elements may includeconstricting elements positioned in one or more electrolyte flow paths.In some cases, the constricting elements are rods.

In another aspect of the embodiments herein, a method for electroplatinga substrate is provided. The method may include (a) receiving asubstantially planar substrate in a substrate holder, where a platingface of the substrate is exposed, and where the substrate holder isconfigured to hold the substrate such that the plating face of thesubstrate is separated from the anode during electroplating, (b)immersing the substrate in electrolyte, where a gap of about 10 mm orless is formed between the plating face of the substrate and an uppersurface of an ionically resistive element, where the ionically resistiveelement is at least coextensive with the plating face of the substrate,and where the ionically resistive element is adapted to provide ionictransport through the ionically resistive element during electroplating,(c) flowing electrolyte in contact with the substrate in the substrateholder (i) from a side inlet, into the gap, and out a side outlet, and(ii) from below the ionically resistive element, through the ionicallyresistive element, into the gap, and out the side outlet, where theinlet and outlet are positioned proximate azimuthally opposed perimeterlocations on the plating face of the substrate, and where the inlet andoutlet are designed or configured to generate cross-flowing electrolytein the gap during electroplating, (d) rotating the substrate holder, and(e) electroplating material onto the plating face of the substrate whileflowing the electrolyte as in (c). The inlet may be separated into twoor more azimuthally distinct and fluidically separated sections, and theflow of electrolyte to the azimuthally distinct sections may beindependently controlled. In some cases, at least two of the sections ofthe inlet receive different electrolyte flow rates.

In some embodiments, flowing electrolyte in operation (c) includesflowing electrolyte at a cross flow velocity of at least about 3 cm/s(e.g., at least about 5 cm/s, at least about 10 cm/s, or at least about20 cm/s) across a center point on or proximate the plating face of thesubstrate. In these or other embodiments, electrolyte may exit theionically resistive element at a velocity of at least about 3 cm/s(e.g., at least about 5 cm/s, or at least about 10 cm/s).

The side outlet in some embodiments may be separated into two or moreazimuthally distinct side outlet sections. The method may also includeflowing electrolyte at different flow rates through at least two of theazimuthally distinct outlet sections. In certain implementations,flowing electrolyte in operation (c)(ii) includes flowing electrolytesuch that it impinges upon the plating face of the substrate. In somecases, flow directing elements may be positioned in the gap. The flowdirecting elements may cause electrolyte to flow in a substantiallylinear flow path from the side inlet to the side outlet. In some cases,these flow directing elements are partitions/fins. The fins may belocated downstream or at least partially downstream of the side inlet.The total flow rate of electrolyte into the gap may be between about1-60 L/min in some cases (e.g., between about 6-60 L/min, or betweenabout 5-25 L/min, or between about 15-25 L/min). In one embodiment, theoverall flow rate of electrolyte into the gap is about 12 L/min. Inanother embodiment, this flow rate is about 20 L/min.

These and other features will be described below with reference to theassociated drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a perspective view of a substrate holding and positioningapparatus for electrochemically treating semiconductor wafers.

FIG. 1B depicts a cross-sectional view of a portion of a substrateholding assembly including a cone and cup.

FIG. 1C depicts a simplified view of an electroplating cell that may beused in practicing the embodiments herein.

FIG. 1D-J illustrate various electroplating apparatus embodiments thatmay be used to enhance cross flow across the face of a substrate, alongwith top views of the flow dynamics achieved when practicing theseembodiments.

FIG. 2 illustrates an exploded view of various parts of anelectroplating apparatus typically present in the cathode chamber inaccordance with certain embodiments disclosed herein.

FIG. 3A shows a close-up view of a cross flow side inlet and surroundinghardware in accordance with certain embodiments herein.

FIG. 3B shows a close-up view of a cross flow outlet, a CIRP manifoldinlet, and surrounding hardware in accordance with various disclosedembodiments.

FIG. 4 depicts a cross-sectional view of various parts of theelectroplating apparatus shown in FIGS. 3A-B.

FIG. 5 shows a cross flow injection manifold and showerhead split into 6individual segments according to certain embodiments.

FIG. 6 shows a top view of a CIRP and associated hardware according toan embodiment herein, focusing especially on the inlet side of the crossflow.

FIG. 7 illustrates a simplified top view of a CIRP and associatedhardware showing both the inlet and outlet sides of the cross flowmanifold according to various disclosed embodiments.

FIGS. 8A-B depict an initial (8A) and revised (8B) design of a crossflow inlet region according to certain embodiments.

FIG. 9 shows an embodiment of a CIRP partially covered by a flowconfinement ring and supported by a frame.

FIG. 10 is a graph of thickness vs. wafer position, illustrating thecenter-to-edge non-uniformity that arises when no cross flow side inletis used.

FIG. 11 is a graph of thickness vs. wafer position, showing theimprovement in center-to-edge uniformity that may be achieved when usinga cross flow side inlet.

FIG. 12 shows various graphs of thickness vs. wafer position,illustrating the improvement in feature shape uniformity that may beachieved using a cross flow side inlet.

FIG. 13 is a graph of bump composition (percent silver) vs. waferposition for the case where no cross flow side inlet is used.

FIG. 14A shows a simplified top view of a CIRP and flow confinement ringwhere no side inlet is used.

FIG. 14B shows a simplified top view of a CIRP, flow confinement ring,and cross flow side inlet according to various embodiments disclosedherein.

FIGS. 15A-B illustrate the cross flow through the cross flow manifoldfor the apparatus shown in FIGS. 14A-B, respectively.

FIGS. 16A-B show modeling results illustrating the cross flow velocityduring plating at a plane near the substrate for the apparatus shown inFIGS. 14A-B, respectively.

FIGS. 17A-B are graphs showing the horizontal cross flow velocity duringplating vs. wafer position for the apparatus shown in FIGS. 14A-B,respectively.

FIGS. 18A-B show modeling results illustrating the cross flow velocityachieved over different parts of the substrate when no plating fluid isdelivered through the cross flow side inlet (18A) and when a certainamount of plating fluid is delivered through the cross flow side inlet(18B).

FIGS. 19A-B show static imprint test results for the cases where nofluid is delivered through the cross flow side inlet (19A), and where acertain amount of fluid is delivered through the cross flow side inlet(19B).

FIG. 20 is a graph showing flowrate vs. cross flow showerhead pressure,where each line was generated using a different set of fluidicadjustment rods restricting flow to either the cross flow injectionmanifold/showerhead, or to the CIRP manifold/CIRP.

FIGS. 21A-B show modeling results illustrating the y-velocity (thetowards-wafer-velocity) of the flow in the cross flow manifold for twodifferent confinement ring/cross flow side inlet designs.

FIG. 21C illustrates modeling results showing the flow pattern achievedin the cross flow manifold for the case shown in FIG. 21A.

FIGS. 22A-B illustrate modeling results showing the cross flow velocityfor two different arrangements of the showerhead holes.

DETAILED DESCRIPTION

In this application, the terms “semiconductor wafer,” “wafer,”“substrate,” “wafer substrate,” and “partially fabricated integratedcircuit” are used interchangeably. One of ordinary skill in the artwould understand that the term “partially fabricated integrated circuit”can refer to a silicon wafer during any of many stages of integratedcircuit fabrication thereon. The following detailed description assumesthe invention is implemented on a wafer. Oftentimes, semiconductorwafers have a diameter of 200, 300 or 450 mm. However, the invention isnot so limited. The work piece may be of various shapes, sizes, andmaterials. In addition to semiconductor wafers, other work pieces thatmay take advantage of this invention include various articles such asprinted circuit boards and the like.

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the presented embodiments.The disclosed embodiments may be practiced without some or all of thesespecific details. In other instances, well-known process operations havenot been described in detail to not unnecessarily obscure the disclosedembodiments. While the disclosed embodiments will be described inconjunction with the specific embodiments, it will be understood that itis not intended to limit the disclosed embodiments.

Described herein are apparatus and methods for electroplating one ormore metals onto a substrate. Embodiments are described generally wherethe substrate is a semiconductor wafer; however the invention is not solimited.

Disclosed embodiments include electroplating apparatus configured for,and methods including, control of electrolyte hydrodynamics duringplating so that highly uniform plating layers are obtained. In specificimplementations, the disclosed embodiments employ methods and apparatusthat create combinations of impinging flow (flow directed at orperpendicular to the work piece surface) and shear flow (sometimesreferred to as “cross flow” or flow with velocity parallel to the workpiece surface).

One embodiment is an electroplating apparatus including the followingfeatures: (a) a plating chamber configured to contain an electrolyte andan anode while electroplating metal onto a substantially planarsubstrate; (b) a substrate holder configured to hold the substantiallyplanar substrate such that a plating face of the substrate is separatedfrom the anode during electroplating; (c) a channeled ionicallyresistive element including a substrate-facing surface that issubstantially parallel to and separated from a plating face of thesubstrate during electroplating, the channeled ionically resistiveelement including a plurality of non-communicating channels, where thenon-communicating channels allow for transport of the electrolytethrough the element during electroplating; and (d) a mechanism forcreating and/or applying a shearing force (cross flow) to theelectrolyte flowing at the plating face of the substrate. Though thewafer is substantially planar, it also typically has one or moremicroscopic trenches and may have one or more portions of the surfacemasked from electrolyte exposure. In various embodiments, the apparatusalso includes a mechanism for rotating the substrate and/or thechanneled ionically resistive element while flowing electrolyte in theelectroplating cell in the direction of the substrate plating face.

In certain implementations, the mechanism for applying cross flow is aninlet with, for example, appropriate flow directing and distributingmeans on or proximate to the periphery of the channeled ionicallyresistive element. The inlet directs cross flowing catholyte along thesubstrate-facing surface of the channeled ionically resistive element.The inlet is azimuthally asymmetric, partially following thecircumference of the channeled ionically resistive element, and havingone or more gaps, and defining a cross flow injection manifold betweenthe channeled ionically resistive element and the substantially planarsubstrate during electroplating. Other elements are optionally providedfor working in concert with the cross flow injection manifold. These mayinclude a cross flow injection flow distribution showerhead and a crossflow confinement ring, which are further described below in conjunctionwith the figures.

In certain embodiments, the apparatus is configured to enable flow ofelectrolyte in the direction towards or perpendicular to a substrateplating face to produce an average flow velocity of at least about 3cm/s (e.g., at least about 5 cm/s or at least about 10 cm/s) exiting theholes of the channeled ionically resistive element duringelectroplating. In certain embodiments, the apparatus is configured tooperate under conditions that produce an average transverse electrolytevelocity of about 3 cm/sec or greater (e.g., about 5 cm/s or greater,about 10 cm/s or greater, about 15 cm/s or greater, or about 20 cm/s orgreater) across the center point of the plating face of the substrate.These flow rates (i.e., the flow rate exiting the holes of the ionicallyresistive element and the flow rate across the plating face of thesubstrate) are in certain embodiments appropriate in an electroplatingcell employing an overall electrolyte flow rate of about 20 L/min and anapproximately 12 inch diameter substrate. The embodiments herein may bepracticed with various substrate sizes. In some cases, the substrate hasa diameter of about 200 mm, about 300 mm, or about 450 mm. Further, theembodiments herein may be practiced at a wide variety of overall flowrates. In certain implementations, the overall electrolyte flow rate isbetween about 1-60 L/min, between about 6-60 L/min, between about 5-25L/min, or between about 15-25 L/min. The flow rates achieved duringplating may be limited by certain hardware constraints, such as the sizeand capacity of the pump being used. One of skill in the art wouldunderstand that the flow rates cited herein may be higher when thedisclosed techniques are practiced with larger pumps.

In some embodiments, the electroplating apparatus contains separatedanode and cathode chambers in which there are different electrolytecompositions, electrolyte circulation loops, and/or hydrodynamics ineach of two chambers. An ionically permeable membrane may be employed toinhibit direct convective transport (movement of mass by flow) of one ormore components between the chambers and maintain a desired separationbetween the chambers. The membrane may block bulk electrolyte flow andexclude transport of certain species such as organic additives whilepermitting transport of ions such as cations. In some embodiments, themembrane contains DuPont's NAFION™ or a related ionically selectivepolymer. In other cases, the membrane does not include an ion exchangematerial, and instead includes a micro-porous material. Conventionally,the electrolyte in the cathode chamber is referred to as “catholyte” andthe electrolyte in the anode chamber is referred to as “anolyte.”Frequently, the anolyte and catholyte have different compositions, withthe anolyte containing little or no plating additives (e.g.,accelerator, suppressor, and/or leveler) and the catholyte containingsignificant concentrations of such additives. The concentration of metalions and acids also often differs between the two chambers. An exampleof an electroplating apparatus containing a separated anode chamber isdescribed in U.S. Pat. Nos. 6,527,920, filed Nov. 3, 2000 [attorneydocket NOVLP007]; 6,821,407, filed Aug. 27, 2002 [attorney docketNOVLP048], and 8,262,871, filed Dec. 17, 2009 [attorney docket NOVLP308]each of which is incorporated herein by reference in its entirety.

In some embodiments, the anode membrane need not include an ion exchangematerial. In some examples, the membrane is made from a micro-porousmaterial such as polyethersulfone manufactured by Koch Membrane ofWilmington, Mass. This membrane type is most notably applicable forinert anode applications such as tin-silver plating and gold plating,but may also be used for soluble anode applications such as nickelplating.

In certain embodiments, and as described more fully elsewhere herein,catholyte is injected into a manifold region, referred to hereafter asthe “CIRP manifold region”, in which electrolyte is fed, accumulates,and then is distributed and passes substantially uniformly through thevarious non-communication channels of the CIRP directly towards thewafer surface.

In the following discussion, when referring to top and bottom features(or similar terms such as upper and lower features, etc.) or elements ofthe disclosed embodiments, the terms top and bottom are simply used forconvenience and represent only a single frame of reference orimplementation of the invention. Other configurations are possible, suchas those in which the top and bottom components are reversed withrespect to gravity and/or the top and bottom components become the leftand right or right and left components.

While some aspects described herein may be employed in various types ofplating apparatus, for simplicity and clarity, most of the examples willconcern wafer-face-down, “fountain” plating apparatus. In suchapparatus, the work piece to plated (typically a semiconductor wafer inthe examples presented herein) generally has a substantially horizontalorientation (which may in some cases vary by a few degrees from truehorizontal for some part of, or during the entire plating process) andmay be powered to rotate during plating, yielding a generally verticallyupward electrolyte convection pattern. Integration of the impinging flowmass from the center to the edge of the wafer, as well as the inherenthigher angular velocity of a rotating wafer at its edge relative to itscenter, creates a radially increasing sheering (wafer parallel) flowvelocity. One example of a member of the fountain plating class ofcells/apparatus is the Sabre® Electroplating System produced by andavailable from Novellus Systems, Inc. of San Jose, Calif. Additionally,fountain electroplating systems are described in, e.g., U.S. Pat. Nos.6,800,187, filed Aug. 10, 2001 [attorney docket NOVLP020] and 8,308,931,filed Nov. 7, 2008 [attorney docket NOVLP299], which are incorporatedherein by reference in their entireties.

The substrate to be plated is generally planar or substantially planar.As used herein, a substrate having features such as trenches, vias,photoresist patterns and the like is considered to be substantiallyplanar. Often these features are on the microscopic scale, though thisis not necessarily always the case. In many embodiments, one or moreportions of the surface of the substrate may be masked from exposure tothe electrolyte.

The following description of FIGS. 1A and 1B provides a generalnon-limiting context to assist in understanding the apparatus andmethods described herein. FIG. 1A provides a perspective view of a waferholding and positioning apparatus 100 for electrochemically treatingsemiconductor wafers. Apparatus 100 includes wafer engaging components(sometimes referred to herein as “clamshell” components). The actualclamshell includes a cup 102 and a cone 103 that enables pressure to beapplied between the wafer and the seal, thereby securing the wafer inthe cup.

Cup 102 is supported by struts 104, which are connected to a top plate105. This assembly (102-105), collectively assembly 101, is driven by amotor 107, via a spindle 106. Motor 107 is attached to a mountingbracket 109. Spindle 106 transmits torque to a wafer (not shown in thisfigure) to allow rotation during plating. An air cylinder (not shown)within spindle 106 also provides vertical force between the cup and cone103 to create a seal between the wafer and a sealing member (lipseal)housed within the cup. For the purposes of this discussion, the assemblyincluding components 102-109 is collectively referred to as a waferholder 111. Note however, that the concept of a “wafer holder” extendsgenerally to various combinations and sub-combinations of componentsthat engage a wafer and allow its movement and positioning.

A tilting assembly including a first plate 115, that is slidablyconnected to a second plate 117, is connected to mounting bracket 109. Adrive cylinder 113 is connected both to plate 115 and plate 117 at pivotjoints 119 and 121, respectively. Thus, drive cylinder 113 providesforce for sliding plate 115 (and thus wafer holder 111) across plate117. The distal end of wafer holder 111 (i.e. mounting bracket 109) ismoved along an arced path (not shown) which defines the contact regionbetween plates 115 and 117, and thus the proximal end of wafer holder111 (i.e. cup and cone assembly) is tilted upon a virtual pivot. Thisallows for angled entry of a wafer into a plating bath.

The entire apparatus 100 is lifted vertically either up or down toimmerse the proximal end of wafer holder 111 into a plating solution viaanother actuator (not shown). Thus, a two-component positioningmechanism provides both vertical movement along a trajectoryperpendicular to an electrolyte and a tilting movement allowingdeviation from a horizontal orientation (parallel to electrolytesurface) for the wafer (angled-wafer immersion capability). A moredetailed description of the movement capabilities and associatedhardware of apparatus 100 is described in U.S. Pat. No. 6,551,487 filedMay 31, 2001 and issued Apr. 22, 2003 [attorney docket NOVLP022], whichis herein incorporated by reference in its entirety.

Note that apparatus 100 is typically used with a particular plating cellhaving a plating chamber which houses an anode (e.g., a copper anode ora non-metal inert anode) and electrolyte. The plating cell may alsoinclude plumbing or plumbing connections for circulating electrolytethrough the plating cell—and against the work piece being plated. It mayalso include membranes or other separators designed to maintaindifferent electrolyte chemistries in an anode compartment and a cathodecompartment. In one embodiment, one membrane is employed to define ananode chamber, which contains electrolyte that is substantially free ofsuppressors, accelerators, or other organic plating additives, or inanother embodiment, where the inorganic plating composition of theanolyte and catholyte are substantially different. Means of transferringanolyte to the catholyte or to the main plating bath by physical means(e.g. direct pumping including values, or an overflow trough) mayoptionally also be supplied.

The following description provides more detail of the cup and coneassembly of the clamshell. FIG. 1B depicts a portion, 101, of assembly100, including cone 103 and cup 102 in cross-section format. Note thatthis figure is not meant to be a true depiction of a cup and coneproduct assembly, but rather a stylized depiction for discussionpurposes. Cup 102 is supported by top plate 105 via struts 104, whichare attached via screws 108. Generally, cup 102 provides a support uponwhich wafer 145 rests. It includes an opening through which electrolytefrom a plating cell can contact the wafer. Note that wafer 145 has afront side 142, which is where plating occurs. The periphery of wafer145 rests on the cup 102. The cone 103 presses down on the back side ofthe wafer to hold it in place during plating.

To load a wafer into 101, cone 103 is lifted from its depicted positionvia spindle 106 until cone 103 touches top plate 105. From thisposition, a gap is created between the cup and the cone into which wafer145 can be inserted, and thus loaded into the cup. Then cone 103 islowered to engage the wafer against the periphery of cup 102 asdepicted, and mate to a set of electrical contacts (not shown in 1B)radially beyond the lip seal 143 along the wafer's outer periphery.

Spindle 106 transmits both vertical force for causing cone 103 to engagea wafer 145 and torque for rotating assembly 101. These transmittedforces are indicated by the arrows in FIG. 1B. Note that wafer platingtypically occurs while the wafer is rotating (as indicated by the dashedarrows at the top of FIG. 1B).

Cup 102 has a compressible lip seal 143, which forms a fluid-tight sealwhen cone 103 engages wafer 145. The vertical force from the cone andwafer compresses lip seal 143 to form the fluid tight seal. The lip sealprevents electrolyte from contacting the backside of wafer 145 (where itcould introduce contaminating species such as copper or tin ionsdirectly into silicon) and from contacting sensitive components ofapparatus 101. There may also be seals located between the interface ofthe cup and the wafer which form fluid-tight seals to further protectthe backside of wafer 145 (not shown).

Cone 103 also includes a seal 149. As shown, seal 149 is located nearthe edge of cone 103 and an upper region of the cup when engaged. Thisalso protects the backside of wafer 145 from any electrolyte that mightenter the clamshell from above the cup. Seal 149 may be affixed to thecone or the cup, and may be a single seal or a multi-component seal.

Upon initiation of plating, cone 103 is raised above cup 102 and wafer145 is introduced to assembly 102. When the wafer is initiallyintroduced into cup 102—typically by a robot arm—its front side, 142,rests lightly on lip seal 143. During plating the assembly 101 rotatesin order to aid in achieving uniform plating. In subsequent figures,assembly 101 is depicted in a more simplistic format and in relation tocomponents for controlling the hydrodynamics of electrolyte at the waferplating surface 142 during plating. Thus, an overview of mass transferand fluid shear at the work piece follows.

As depicted in FIG. 1C, a plating apparatus 150 includes a plating cell155 which houses anode 160. In this example, electrolyte 175 is flowedinto cell 155 centrally through an opening in anode 160, and theelectrolyte passes through a channeled ionically resistive element 170having vertically oriented (non-intersecting) through holes throughwhich electrolyte flows and then impinges on wafer 145, which is heldin, positioned and moved by, wafer holder 101. Channeled ionicallyresistive elements such as 170 provide uniform impinging flow upon thewafer plating surface. In accordance with certain embodiments describedherein, apparatus utilizing such channeled ionically resistive elementsare configured and/or operated in a manner that facilitates high rateand high uniformity plating across the face of the wafer, includingplating under high deposition rate regimes such as for WLP and TSVapplications. Any or all of the various embodiments described can beimplemented in the context of Damascene as well as TSV and WLPapplications.

FIGS. 1D-J relate to certain techniques that may be used to encouragecross flow across the face of a substrate being plated. Varioustechniques described in relation to these figures present alternativestrategies for encouraging cross flow. As such, certain elementsdescribed in these figures are optional, and are not present in allembodiments.

In some embodiments, electrolyte flow ports are configured to aidtransverse flow, alone or in combination with a flow shaping plate and aflow diverter as described herein. Various embodiments are describedbelow in relation to a combination with a flow shaping plate and a flowdiverter, but the invention is not so limited. Note that in certainembodiments it is believed that the magnitude of the electrolyte flowvectors across the wafer surface are larger proximate the vent or gapand progressively smaller across the wafer surface, being smallest atthe interior of the pseudo chamber furthest from the vent or gap. Asdepicted in FIG. 1D, by using appropriately configured electrolyte flowports, the magnitude of these transverse flow vectors is more uniformacross the wafer surface.

FIG. 1E depicts a simplified cross-section of a plating cell, 700,having a wafer holder, 101, which is partially immersed in anelectrolyte, 175, in plating bath 155. Plating cell 700 includes a flowshaping plate, 705, such as those described herein. An anode, 160,resides below plate 705. On top of plate 705 is a flow diverter, 315. Inthis figure, the vent or gap (outlet) in the flow diverter is on theright side of the diagram and thus imparts transverse flow from left toright as indicated by the largest dotted arrow. A series of smallervertical arrows indicate flow through the vertically oriented throughholes in plate 705. Also below plate 705 are a series of electrolyteinlet flow ports, 710, that introduce electrolyte into the chamber belowplate 705. In this figure, there is no membrane separating an anolyteand catholyte chamber, but this can also be included in such platingcells without departing from the scope of this description.

In this example, flow ports 710 are distributed radially about theinterior wall of cell 155. In certain embodiments, in order to enhancethe transverse flow across the wafer plating surface, one or more ofthese flow ports is blocked, for example, flow ports on the right handside (as drawn), proximate the vent or gap in the pseudo chamber formedbetween the wafer, plate 705 and flow diverter 315. In this way,although impinging flow is permitted through all the through holes inplate 705, the pressure at the left side, distal of the gap or vent inthe pseudo chamber, is higher and thus the transverse flow across thewafer surface (in this example shown as left to right flow) is enhanced.In certain embodiments, the blocked flow ports are positioned about anazimuth that is at least equal to the azimuth of the segmented portionof the flow diverter. In a specific embodiment, the electrolyte flowports on a 90° azimuthal section of the circumference of the electrolytechamber below the flow shaping plate are blocked. In one embodiment,this 90° azimuthal section is registered with the open segment (outlet)of the flow diverter annulus.

In other embodiments, the electrolyte inlet flow port or ports areconfigured to favor higher pressure in the area below the portion of theflow diverter distal of the vent or gap (indicated by Y in FIG. 1E). Insome instances, simply physically blocking (e.g., via one or more shutoff valves) selected inlet ports is more convenient and flexible thandesigning a cell with particularly configured electrolyte inlet ports.This is true because the configuration of the flow shaping plate and theassociated flow diverter can change with different desired platingresults and thus it is more flexible to be able to vary the electrolyteinlet configuration on a single plating cell.

In other embodiments, with or without blocking one or more electrolyteinlet ports, a dam, baffle or other physical structure is configured tofavor higher pressure in the area below the portion of the flow diverterdistal of the vent or gap. For example, referring to FIG. 1F, a baffle,720, is configured to favor higher pressure in the area below theportion of the flow diverter distal of the vent or gap (indicated by Yin FIG. 7C). FIG. 1G is a top view of plating cell 155, without waferholder 101, flow diverter 315 or flow shaping plate 705, showing thatbaffle 720 promotes electrolyte flow emanating from ports 720 toconfluence at area Y and thus increase pressure in that area (supra).One of ordinary skill in the art would appreciate that a physicalstructure may be oriented in a number of different ways, e.g. havinghorizontal, vertical, sloped or other elements in order to channel flowof the electrolyte in order to create a higher pressure region asdescribed and thus promote transverse flow across the wafer surface inthe pseudo chamber where the shear flow vectors are substantiallyuniform.

Some embodiments do include electrolyte inlet flow ports configured fortransverse flow enhancement in conjunction with flow shaping plate andflow diverter assemblies. FIG. 1H depicts a cross-section of componentsof a plating apparatus, 725, for plating copper onto a wafer, 145, whichis held, positioned and rotated by wafer holder 101. Apparatus 725includes a plating cell, 155, which is dual chamber cell, having ananode chamber with a copper anode, 160, and anolyte. The anode chamberand cathode chamber are separated by a cationic membrane 740 which issupported by a support member 735. Plating apparatus 725 includes a flowshaping plate, 410, as described herein. A flow diverter, 325, is on topof flow shaping plate 410, and aides in creating transverse shear flowas described herein. Catholyte is introduced into the cathode chamber(above membrane 740) via flow ports 710. From flow ports 710, catholytepasses through flow plate 410 as described herein and produces impingingflow onto the plating surface of wafer 145. In addition to catholyteflow ports 710, an additional flow port, 710 a, introduces catholyte atits exit at a position distal to the vent or gap of flow diverter 325.In this example, flow port 710 a's exit is formed as a channel in flowshaping plate 410. The functional result is that catholyte flow isintroduced directly into the pseudo chamber formed between the flowplate and the wafer plating surface in order to enhance transverse flowacross the wafer surface and thereby normalize the flow vectors acrossthe wafer (and flow plate 410).

FIG. 1I depicts a flow diagram depicting the flow port 710 a (from FIG.1H). As seen in FIG. 1I, flow port 710 a's exit spans 90 degrees of theinner circumference of flow diverter 325. One of ordinary skill in theart would appreciate that the dimensions, configuration and location ofport 710 a may vary without escaping the scope of the invention. One ofskill in the art would also appreciate that equivalent configurationswould include having the catholyte exit from a port or channel in flowdiverter 325 and/or in combination with a channel such as depicted inFIG. 1H (in flow plate 410). Other embodiments include one or more portsin the (lower) side wall of a flow diverter, i.e. that side wall nearestthe flow shaping plate top surface, where the one or more ports arelocated in a portion of the flow diverter opposite the vent or gap. FIG.1J depicts a flow diverter, 750, assembled with a flow shaping plate410, where flow diverter 750 has catholyte flow ports, 710 b, thatsupply electrolyte from the flow diverter opposite the gap of the flowdiverter. Flow ports such as 710 a and 710 b may supply electrolyte atany angle relative to the wafer plating surface or the flow shapingplate top surface. The one or more flow ports can deliver impinging flowto the wafer surface and/or transverse (shear) flow.

In one embodiment, for example as described in relation to FIGS. 1H-J, aflow shaping plate as described herein is used in conjunction with aflow diverter, where a flow port configured for enhanced transverse flow(as described herein) is also used with the flow plate/flow diverterassembly. In one embodiment the flow shaping plate has non-uniform holedistribution, in one embodiment, a spiral hole pattern.

Terminology and Flow Paths

Numerous figures are provided to further illustrate and explain theembodiments disclosed herein. The figures include, among other things,various drawings of the structural elements and flow paths associatedwith a disclosed electroplating apparatus. These elements are givencertain names/reference numbers, which are used consistently indescribing FIGS. 2 through 22A-B.

The following embodiments assume, for the most part, that electroplatingapparatus includes a separate anode chamber. The described features arecontained in a cathode chamber, which includes a membrane frame 274 andmembrane 202 that separate the anode chamber from the cathode chamber.Any number of possible anode and anode chamber configurations may beemployed. In the following embodiments, the catholyte contained in thecathode chamber is largely located either in a cross flow manifold 226or in the channeled ionically resistive plate manifold 208 or inchannels 258 and 262 for delivering catholyte to these two separatemanifolds.

Much of the focus in the following description is on controlling thecatholyte in the cross flow manifold 226. The catholyte enters the crossflow manifold 226 through two separate entry points: (1) the channels inthe channeled ionically resistive plate 206 and (2) cross flowinitiating structure 250. The catholyte arriving in the cross flowmanifold 226 via the channels in the CIRP 206 is directed toward theface of the work piece, typically in a substantially perpendiculardirection. Such channel delivered catholyte may form small jets thatimpinge on the face of the work piece, which is typically rotatingslowly (e.g., between about 1 to 30 rpm) with respect to the channeledplate. The catholyte arriving in the cross flow manifold 226 via thecross flow initiating structure 250 is, in contrast, directedsubstantially parallel to the face of the work piece.

As indicated in the discussion above, a “channeled ionically resistiveplate” 206 (or “channeled ionically resistive element” or “CIRP”) ispositioned between the working electrode (the wafer or substrate) andthe counter electrode (the anode) during plating, in order to shape theelectric field and control electrolyte flow characteristics. Variousfigures herein show the relative position of the channeled ionicallyresistive plate 206 with respect to other structural features of thedisclosed apparatus. One example of such an ionically resistive element206 is described in U.S. Pat. No. 8,308,931, filed Nov. 7, 2008[attorney docket NOVLP299], which was previously incorporated byreference herein in its entirety. The channeled ionically resistiveplate described therein is suitable to improve radial plating uniformityon wafer surfaces such as those containing relatively low conductivityor those containing very thin resistive seed layers. Further aspects ofcertain embodiments of the channeled element are described below.

A “membrane frame” 274 (sometimes referred to as an anode membrane framein other documents) is a structural element employed in some embodimentsto support a membrane 202 that separates an anode chamber from a cathodechamber. It may have other features relevant to certain embodimentsdisclosed herein. Particularly, with reference to the embodiments of thefigures, it may include flow channels 258 and 262 for deliveringcatholyte toward a cross flow manifold 226 and showerhead 242 configuredto deliver cross flowing catholyte to the cross flow manifold 226. Themembrane frame 274 may also contain a cell weir wall 282, which isuseful in determining and regulating the uppermost level of thecatholyte. Various figures herein depict the membrane frame 274 in thecontext of other structural features associated with the disclosed crossflow apparatus.

Turning to FIG. 2, the membrane frame 274 is a rigid structural memberfor holding a membrane 202 that is typically an ion exchange membraneresponsible for separating an anode chamber from a cathode chamber. Asexplained, the anode chamber may contain electrolyte of a firstcomposition while the cathode chamber contains electrolyte of a secondcomposition. The membrane frame 274 may also include a plurality offluidic adjustment rods 270 (sometimes referred to as flow constrictingelements) which may be used to help control fluid delivery to thechanneled ionically resistive element 206. The membrane frame 274defines the bottom-most portion of the cathode chamber and the uppermostportion of the anode chamber. The described components are all locatedon the work piece side of an electrochemical plating cell above theanode chamber and the anode chamber membrane 202. They can all be viewedas being part of a cathode chamber. It should be understood, however,that certain implementations of a cross flow injection apparatus do notemploy a separated anode chamber, and hence a membrane frame 274 is notessential.

Located generally between the work piece and the membrane frame 274 isthe channeled ionically resistive plate 206, as well as a cross flowring gasket 238 and wafer cross flow confinement ring 210, which mayeach be affixed to the channeled ionically resistive plate 206. Morespecifically, the cross flow ring gasket 238 may be positioned directlyatop the CIRP 206, and the wafer cross flow confinement ring 210 may bepositioned over the cross flow ring gasket 238 and affixed to a topsurface of the channeled ionically resistive plate 206, effectivelysandwiching the gasket 238. Various figures herein show the cross flowconfinement ring 210 arranged with respect to the channeled ionicallyresistive plate 206.

The upper most relevant structural feature of the present disclosure, asshown in FIG. 2, is a work piece or wafer holder. In certainembodiments, the work piece holder may be a cup 254, which is commonlyused in cone and cup clamshell type designs such as the design embodiedin Novellus Systems' Sabre® electroplating tool mentioned above. FIGS. 2and 8A-8B, for example, show the relative orientation of the cup 254with respect to other elements of the apparatus.

FIG. 3A shows a close-up cross sectional view of a cross flow inlet sideaccording to an embodiment disclosed herein. FIG. 3B shows a close-upcross sectional view of the cross flow outlet side according to anembodiment herein. FIG. 4 shows a cross-sectional view of a platingapparatus showing both the inlet and outlet sides, in accordance withcertain embodiments herein. During a plating process, catholyte fillsand occupies the region between the top of the membrane 202 on themembrane frame 274 and the membrane frame weir wall 282. This catholyteregion can be subdivided into three sub-regions: 1) a channeledionically resistive plate manifold region 208 below the CIRP 206 and(for designs employing an anode chamber cationic membrane) above theseparated-anode-chambers cationic-membrane 202 (this element is alsosometimes referred to as a lower manifold region 208), 2) the cross flowmanifold region 226, between the wafer and the upper surface of the CIRP206, and 3) an upper cell region or “electrolyte containment region”,outside of the clamshell/cup 254 and inside the cell weir wall 282(which is a physical part of the membrane frame 274). When the wafer isnot immersed and the clamshell/cup 254 is not in the down position, thesecond region and third region are combined into one region.

Region (2) above, between the top of the channeled ionically resistiveplate 206 and the bottom of the workpiece when installed in theworkpiece holder 254 contains catholyte and is referred to as the “crossflow manifold” 226. In some embodiments, catholyte enters the cathodechamber via a single inlet port. In other embodiments, catholyte entersthe cathode chamber through one or more ports located elsewhere in theplating cell. In some cases, there is a single inlet for the bath of thecell, peripheral to the anode chamber and cut out of the anode chambercell walls. This inlet connects to a central catholyte inlet manifold atthe base of the cell and anode chamber. In certain disclosedembodiments, that main catholyte manifold chamber feeds a plurality ofcatholyte chamber inlet holes (e.g., 12 catholyte chamber inlet holes).In various cases, these catholyte chamber inlet holes are divided intotwo groups: one group which feeds catholyte to a cross flow injectionmanifold 222, and a second group which feeds catholyte to the CIRPmanifold 208. FIG. 3B shows a cross section of a single inlet holefeeding the CIRP manifold 208 through channel 262. The dotted lineindicates the path of fluid flow.

The separation of catholyte into two different flow paths or streamsoccurs at the base of the cell in the central catholyte inlet manifold(not shown). That manifold is fed by a single pipe connected to the baseof the cell. From the main catholyte manifold, the flow of catholyteseparates into two streams: 6 of the 12 feeder holes, located on oneside of the cell, lead to source the CIRP manifold region 208 andeventually supply the impinging catholyte flow through the CIRP'svarious microchannels. The other 6 holes also feed from the centralcatholyte inlet manifold, but then lead to the cross flow injectionmanifold 222, which then feeds the cross flow shower head's 242distribution holes 246 (which may number more than 100). After leavingthe cross flow shower head holes 246, the catholyte's flow directionchanges from (a) normal to the wafer to (b) parallel to the wafer. Thischange in flow occurs as the flow impinges upon and is confined by asurface in the cross flow confinement ring 210 inlet cavity 250.Finally, upon entering the cross flow manifold region 226, the twocatholyte flows, initially separated at the base of the cell in thecentral catholyte inlet manifold, are rejoined.

In the embodiments shown in the figures, a fraction of the catholyteentering the cathode chamber is provided directly to the channeledionically resistive plate manifold 208 and a portion is provideddirectly to the cross flow injection manifold 222. At least some, andoften but not always all of the catholyte delivered to the channeledionically resistive plate manifold 208 and then to the CIRP lowersurface passes through the various microchannels in the plate 206 andreaches the cross flow manifold 226. The catholyte entering the crossflow manifold 226 through the channels in the channeled ionicallyresistive plate 206 enters the cross flow manifold as substantiallyvertically directed jets (in some embodiments the channels are made atan angle, so they are not perfectly normal to the surface of the wafer,e.g., the angle of the jet may be up to about 45 degrees with respect tothe wafer surface normal). The portion of the catholyte that enters thecross flow injection manifold 222 is delivered directly to the crossflow manifold 226 where it enters as a horizontally oriented cross flowbelow the wafer. On its way to the cross flow manifold 226, the crossflowing catholyte passes through the cross flow injection manifold 222and the cross flow shower head plate 242 (which, e.g., contains about139 distributed holes 246 having a diameter of about 0.048″), and isthen redirected from a vertically upwards flow to a flow parallel to thewafer surface by the actions/geometry of thecross-flow-confinement-ring's 210 entrance cavity 250.

The absolute angles of the cross flow and the jets need not be exactlyhorizontal or exactly vertical or even oriented at exactly 90° with oneanother. In general, however, the cross flow of catholyte in the crossflow manifold 226 is generally along the direction of the work piecesurface and the direction of the jets of catholyte emanating from thetop surface of the microchanneled ionically resistive plate 206generally flow towards/perpendicular to the surface of the work piece.

As mentioned, the catholyte entering the cathode chamber is dividedbetween (i) catholyte that flows from the channeled ionically resistiveplate manifold 208, through the channels in the CIRP 206 and then intothe cross flow manifold 226 and (ii) catholyte that flows into the crossflow injection manifold 222, through the holes 246 in the showerhead242, and then into the cross flow manifold 226. The flow directlyentering from the cross flow injection manifold region 222 may enter viathe cross flow confinement ring entrance ports, sometimes referred to ascross flow side inlets 250, and emanate parallel to the wafer and fromone side of the cell. In contrast, the jets of fluid entering the crossflow manifold region 226 via the microchannels of the CIRP 206 enterfrom below the wafer and below the cross flow manifold 226, and thejetting fluid is diverted (redirected) within the cross flow manifold226 to flow parallel to the wafer and towards the cross flow confinementring exit port 234, sometimes also referred to as the cross flow outletor outlet.

In some embodiments, the fluid entering the cathode chamber is directedinto multiple channels 258 and 262 distributed around the periphery ofthe cathode chamber portion of the electroplating cell chamber (often aperipheral wall). In a specific embodiment, there are 12 such channelscontained in the wall of the cathode chamber.

The channels in the cathode chamber walls may connect to corresponding“cross flow feed channels” in the membrane frame. Some of these feedchannels 262 deliver catholyte directly to the channeled ionicallyresistive plate manifold 208. As mentioned, the catholyte provided tothis manifold subsequently passes through the small vertically orientedchannels of the channeled ionically resistive plate 206 and enters thecross flow manifold 226 as jets of catholyte.

As mentioned, in an embodiment depicted in the figures, catholyte feedsthe “CIRP manifold chamber” 208 through 6 of the 12 catholyte feederlines/tubes. Those 6 main tubes or lines 262 feeding the CIRP manifold208 reside below the cross flow confinement ring's exit cavity 234(where the fluid passes out of the cross flow manifold region 226 belowthe wafer), and opposite all the cross flow manifold components (crossflow injection manifold 222, showerhead 242, and confinement ringentrance cavity 250).

As depicted in various figures, some cross flow feed channels 258 in themembrane frame lead directly to the cross flow injection manifold 222(e.g., 6 of 12). These cross flow feed channels 258 start at the base ofthe anode chamber of the cell and then pass through matching channels ofthe membrane frame 274 and then connect with corresponding cross flowfeed channels 258 on the lower portion of the channeled ionicallyresistive plate 206. See FIG. 3A, for example.

In a specific embodiment, there are six separate feed channels 258 fordelivering catholyte directly to the cross flow injection manifold 222and then to the cross flow manifold 226. In order to effect cross flowin the cross flow manifold 226, these channels 258 exit into the crossflow manifold 226 in an azimuthally non-uniform manner. Specifically,they enter the cross flow manifold 226 at a particular side or azimuthalregion of the cross flow manifold 226. In a specific embodiment depictedin FIG. 3A, the fluid paths 258 for directly delivering catholyte to thecross flow injection manifold 222 pass through four separate elementsbefore reaching the cross flow injection manifold 222: (1) dedicatedchannels in the cell's anode chamber wall, (2) dedicated channels in themembrane frame 274, (3) dedicated channels the channeled ionicallyresistive element 206 (i.e., not the 1-D channels used for deliveringcatholyte from the CIRP manifold 208 to the cross flow manifold 226),and finally, (4) fluid paths in the wafer cross flow confinement ring210.

As mentioned, the portions of the flow paths passing through themembrane frame 274 and feeding the cross flow injection manifold 222 arereferred to as cross flow feed channels 258 in the membrane frame. Theportions of the flow paths passing through the microchanneled ionicallyresistive plate 206 and feeding the CIRP manifold are referred to ascross flow feed channels 262 feeding the channeled ionically resistiveplate manifold 208, or CIRP manifold feed channels 262. In other words,the term “cross flow feed channel” includes both the catholyte feedchannels 258 feeding the cross flow injection manifold 222 and thecatholyte feed channels 262 feeding the CIRP manifold 208. Onedifference between these flows 258 and 262 was noted above: thedirection of the flow through the CIRP 206 is initially directed at thewafer and is then turned parallel to the wafer due to the presence ofthe wafer and the cross flow confinement ring 210, whereas the crossflow portion coming from the cross flow injection manifold 222 and outthrough the cross flow confinement ring entrance ports 250 startssubstantially parallel to the wafer. While not wishing to be held to anyparticular model or theory, this combination and mixing of impinging andparallel flow is believed to facilitate substantially improved flowpenetration within a recessed/embedded feature and thereby improve themass transfer. By creating a spatially uniform convective flow fieldunder the wafer and rotating the wafer, each feature, and each die,exhibits a nearly identical flow pattern over the course of the rotationand the plating process.

The flow path within the channeled ionically resistive plate 206 thatdoes not pass through the plate's microchannels (instead entering thecross flow manifold 226 as flow parallel to the face of the wafer)begins in a vertically upward direction as it passes through the crossflow feed channel 258 in the plate 206, and then enters a cross flowinjection manifold 222 formed within the body of the channeled ionicallyresistive plate 206. The cross flow injection manifold 222 is anazimuthal cavity which may be a dug out channel within the plate 206that can distribute the fluid from the various individual feed channels258 (e.g., from each of the individual 6 cross flow feed channels) tothe various multiple flow distribution holes 246 of the cross flowshower head plate 242. This cross flow injection manifold 222 is locatedalong an angular section of the peripheral or edge region of thechanneled ionically resistive plate 206. See for example FIGS. 3A and4-6. In certain embodiments, the cross flow injection manifold 222 formsa C-shaped structure over an angle of about 90 to 180° of the plate'sperimeter region. In certain embodiments, the angular extent of thecross flow injection manifold 222 is about 120 to about 170°, and in amore specific embodiment is between about 140 and 150°. In these orother embodiments, the angular extent of the cross flow injectionmanifold 222 is at least about 90°. In many implementations, theshowerhead 242 spans approximately the same angular extent as the crossflow injection manifold 222. Further, the overall inlet structure 250(which in many cases includes one or more of the cross flow injectionmanifold 222, the showerhead 242, the showerhead holes 246, and anopening in the cross flow confinement ring) may span these same angularextents.

In some embodiments, the cross flow in the injection manifold 222 formsa continuous fluidically coupled cavity within the channeled ionicallyresistive plate 206. In this case all of the cross flow feed channels258 feeding the cross flow injection manifold (e.g., all 6) exit intoone continuous and connected cross flow injection manifold chamber. Inother embodiments, the cross flow injection manifold 222 and/or thecross flow showerhead 242 are divided into two or more angularlydistinct and completely or partially separated segments, as shown inFIG. 5 (which shows 6 separated segments). In some embodiments, thenumber of angularly separated segments is between about 1-12, or betweenabout 4-6. In a specific embodiment, each of these angularly distinctsegments is fluidically coupled to a separate cross flow feed channel258 disposed in the channeled ionically resistive plate 206. Thus, forexample, there may be six angularly distinct and separated subregionswithin the cross flow injection manifold 222. In certain embodiments,each of these distinct subregions of the cross flow injection manifold222 has the same volume and/or the same angular extent.

In many cases, catholyte exits the cross flow injection manifold 222 andpasses through a cross flow showerhead plate 242 having many angularlyseparated catholyte outlet ports (holes) 246. See for example FIGS. 2,3A-B and 6.=. In certain embodiments, the cross flow showerhead plate242 is integrated into the channeled ionically resistive plate 206, asshown in FIG. 6 for example. In some embodiments the showerhead plate242 is glued, bolted, or otherwise affixed to the top of the cross flowinjection manifold 222 of the channeled ionically resistive plate 206.In certain embodiments, the top surface of the cross flow showerhead 242is flush with or slightly elevated above a plane or top surface of thechanneled ionically resistive plate 206. In this manner, catholyteflowing through the cross flow injection manifold 222 may initiallytravel vertically upward through the showerhead holes 246 and thenlaterally under the cross flow confinement ring 210 and into the crossflow manifold 226 such that the catholyte enters the cross flow manifold226 in a direction that is substantially parallel with the top face ofthe channeled ionically resistive plate. In other embodiments, theshowerhead 242 may be oriented such that catholyte exiting theshowerhead holes 246 is already traveling in a wafer-parallel direction.

In a specific embodiment, the cross flow showerhead 242 has 139angularly separated catholyte outlet holes 246. More generally, anynumber of holes that reasonably establish uniform cross flow within thecross flow manifold 226 may be employed. In certain embodiments, thereare between about 50 and about 300 such catholyte outlet holes 246 inthe cross flow showerhead 242. In certain embodiments, there are betweenabout 100 and 200 such holes. In certain embodiments, there are betweenabout 120 and 160 such holes. Generally, the size of the individualports or holes 246 can range from about 0.020″ to 0.10″, morespecifically from about 0.03″ to 0.06″ in diameter.

In certain embodiments, these holes 246 are disposed along the entireangular extent of the cross flow showerhead 242 in an angularly uniformmanner (i.e. the spacing between the holes 246 is determined by a fixedangle between the cell center and two adjacent holes). See for exampleFIGS. 3A and 7. In other embodiments, the holes 246 are distributedalong the angular extent in an angularly non-uniform manner. In furtherembodiments, the angularly non-uniform hole distribution is neverthelessa linearly (“x” direction”) uniform distribution. Put another way, inthis latter case, the hole distribution is such that the holes arespaced equally far apart if projected onto an axis perpendicular to thedirection of cross flow (this axis is the “x” direction). Each hole 246is positioned at the same radial distance from the cell center, and isspaced the same distance in the “x” direction from adjacent holes. Thenet effect of having these angularly non-uniform holes 246 is that theoverall cross flow pattern is much more uniform. These two types ofarrangements for the cross flow shower head holes 246 are examinedfurther in the Experimental section, below. See FIG. 22B and theassociated discussion below.

In certain embodiments, the direction of the catholyte exiting the crossflow showerhead 242 is further controlled by a wafer cross flowconfinement ring 210. In certain embodiments, this ring 210 extends overthe full circumference of the channeled ionically resistive plate 206.In certain embodiments, a cross section of the cross flow confinementring 210 has an L-shape, as shown in FIGS. 3A and 4. In certainembodiments, the wafer cross flow confinement ring 210 contains a seriesof flow directing elements such as directional fins 266 in fluidiccommunication with the outlet holes 246 of the cross flow showerhead242. More specifically, the directional fins 266 define largelysegregated fluid passages under an upper surface of the wafer cross flowconfinement ring 210 and between adjacent directional fins 266. In somecases, the purpose of the fins 266 is to redirect and confine flowexiting from the cross flow showerhead holes 246 from an otherwiseradially inward direction to a “left to right” flow trajectory (leftbeing the inlet side 250 of the cross flow, right being the outlet side234). This helps to establish a substantially linear cross flow pattern.The catholyte exiting the holes 246 of the cross flow showerhead 242 isdirected by the directional fins 266 along a flow streamline caused bythe orientation of the directional fins 266. In certain embodiments, allthe directional fins 266 of the wafer cross flow confinement ring 210are parallel to one another. This parallel arrangement helps toestablish a uniform cross flow direction within the cross flow manifold226. In various embodiments, the directional fins 226 of the wafer crossflow confinement ring 210 are disposed both along the inlet 250 andoutlet 234 side of the cross flow manifold 226. This is illustrated inthe top view of FIG. 7, for example.

As indicated, catholyte flowing in the cross flow manifold 226 passesfrom an inlet region 250 of the wafer cross flow confinement ring 210 toan outlet side 234 of the ring 210, as shown in FIGS. 3B and 4. At theoutlet side 234, in certain embodiments, there are multiple directionalfins 266 that may be parallel to and may align with the directional fins266 on the inlet side. The cross flow passes through channels created bythe directional fins 266 on the outlet side 234 and then ultimately anddirectly out of the cross flow manifold 226. The flow then passes intoanother region of the cathode chamber generally radially outwards andbeyond the wafer holder 254 and cross flow confinement ring 210, withfluid collected and temporarily retained by the upper weir wall 282 ofthe membrane frame before flowing over the weir 282 for collection andrecirculation. It should therefore be understood that the figures (e.g.,FIGS. 3A, 3B and 4) show only a partial path of the entire circuit ofcatholyte entering and exiting the cross flow manifold. Note that, inthe embodiment depicted in FIGS. 3B and 4, for example, fluid exitingfrom the cross flow manifold 226 does not pass through small holes orback through channels analogous to the feed channels 258 on the inletside, but rather passes outward in a generally parallel-to-the waferdirection as it is accumulated in the aforementioned accumulationregion.

FIG. 6 shows a top view of the cross flow manifold 226 depicting anembedded cross flow injection manifold 222 within the channeledionically resistive plate 206, along with the showerhead 242 and 139outlet holes 246. All six fluidic adjustment rods 270 for the cross flowinjection manifold flow are also shown. The cross flow confinement ring210 is not installed in this depiction, but the outline of the crossflow confinement ring sealing gasket 238, which seals between the crossflow confinement ring 210 and the upper surface of the CIRP 206, isshown. Other elements which are shown in FIG. 6 include the cross flowconfinement ring fasteners 218, membrane frame 274, and screw holes 278on the anode side of the CIRP 206 (which may be used for a cathodicshielding insert, for example).

In some embodiments, the geometry of the cross flow confinement ringoutlet 234 may be tuned in order to further optimize the cross flowpattern. For example, a case in which the cross flow pattern diverges tothe edge of the confinement ring 210 may be corrected by reducing theopen area in the outer regions of the cross flow confinement ring outlet234. In certain embodiments, the outlet manifold 234 may includeseparated sections or ports, much like the cross flow injection manifold222. In some embodiments, the number of outlet sections is between about1-12, or between about 4-6. The ports are azimuthally separated,occupying different (usually adjacent) positions along the outletmanifold 234. The relative flow rates through each of the ports may beindependently controlled in some cases. This control may be achieved,for example, by using control rods 270 similar to the control rodsdescribed in relation to the inlet flow. In another embodiment, the flowthrough the different sections of the outlet can be controlled by thegeometry of the outlet manifold. For example, an outlet manifold thathas less open area near each side edge and more open area near thecenter would result in a solution flow pattern where more flow exitsnear the center of the outlet and less flow exits near the edges of theoutlet. Other methods of controlling the relative flow rates through theports in the outlet manifold 234 may be used as well (e.g., pumps,etc.).

As mentioned, bulk catholyte entering the catholyte chamber is directedseparately into the cross flow injection manifold 222 and the channeledionically resistive plate manifold 208 through multiple channels 258 and262, e.g., 12 separate channels. In certain embodiments, the flowsthrough these individual channels 258 and 262 are independentlycontrolled from one another by an appropriate mechanism. In someembodiments, this mechanism involves separate pumps for delivering fluidinto the individual channels. In other embodiments, a single pump isused to feed a main catholyte manifold, and various flow restrictionelements that are adjustable may be provided in one or more of thechannels feeding the flow path provided so as to modulate the relativeflows between the various channels 258 and 262 and between the crossflow injection manifold 222 and CIRP manifold 208 regions and/or alongthe angular periphery of the cell. In various embodiments depicted inthe figures, one or more fluidic adjustment rods 270 (sometimes alsoreferred to as flow control elements) are deployed in the channels whereindependent control is provided. In the depicted embodiments, thefluidic adjustment rod 270 provides an annular space in which catholyteis constricted during its flow toward the cross flow injection manifold222 or the channeled ionically resistive plate manifold 208. In a fullyretracted state, the fluidic adjustment rod 270 provides essentially noresistance to flow. In a fully engaged state, the fluidic adjustment rod270 provides maximal resistance to flow, and in some implementationsstops all flow through the channel. In intermediate states or positions,the rod 270 allows intermediate levels of constriction of the flow asfluid flows through a restricted annular space between the channel'sinner diameter and the fluid adjustment rod's outer diameter.

In some embodiments, the adjustment of the fluidic adjustment rods 270allows the operator or controller of the electroplating cell to favorflow to either the cross flow injection manifold 222 or to the channeledionically resistive plate manifold 208. In certain embodiments,independent adjustment of the fluidics adjustment rods 270 in thechannels 258 that deliver catholyte directly to the cross flow injectionmanifold 222 allows the operator or controller to control the azimuthalcomponent of fluid flow into the cross flow manifold 226. The effect ofthese adjustments are discussed further in the Experimental sectionbelow.

FIGS. 8A-B show cross sectional views of a cross flow injection manifold222 and corresponding cross flow inlet 250 relative to a plating cup254. The position of the cross flow inlet 250 is defined, at least inpart, by the position of the cross flow confinement ring 210.Specifically, the inlet 250 may be considered to begin where the crossflow confinement ring 210 terminates. Note that in the case of aninitial design, seen in FIG. 8A, the confinement ring 210 terminationpoint (and inlet 250 commencement point) was under the edge of thewafer, whereas in a revised design, seen in FIG. 8B, thetermination/commencement point is under the plating cup and furtherradially outward from the wafer edge, as compared to the initial design.Also, the cross flow injection manifold 222 in the earlier design had astep in the cross flow ring cavity (where the generally leftward arrowbegins rising upwards) which potentially formed some unwanted turbulencenear that point of fluid entry into the cross flow manifold region 226.On wafer data as well as modeling results confirmed these beliefs, asdiscussed in the Experimental section below. Therefore, it is beneficialto minimize the expansion of the fluid trajectories near the wafer edgeand allow the plating solution to transition from the cross flowinjection manifold region 222 and enter the increased cross sectionalarea of the cross flow manifold region 226 by providing some distance(e.g., about 10-15 mm) for the solution flow to become more uniformbefore flowing across the wafer surface.

The disclosed apparatus may be configured to perform the methodsdescribed herein. A suitable apparatus includes hardware as describedand shown herein and one or more controllers having instructions forcontrolling process operations in accordance with the present invention.The apparatus will include one or more controllers for controlling,inter alia, the positioning of the wafer in the cup 254 and cone, thepositioning of the wafer with respect to the channeled ionicallyresistive plate 206, the rotation of the wafer, the delivery ofcatholyte into the cross flow manifold 226, delivery of catholyte intothe CIRP manifold 208, delivery of catholyte into the cross flowinjection manifold 222, the resistance/position of the fluidicadjustment rods 270, the delivery of current to the anode and wafer andany other electrodes, the mixing of electrolyte components, the timingof electrolyte delivery, inlet pressure, plating cell pressure, platingcell temperature, wafer temperature, and other parameters of aparticular process performed by a process tool.

A system controller will typically include one or more memory devicesand one or more processors configured to execute the instructions sothat the apparatus will perform a method in accordance with the presentinvention. The processor may include a central processing unit (CPU) orcomputer, analog and/or digital input/output connections, stepper motorcontroller boards, and other like components. Machine-readable mediacontaining instructions for controlling process operations in accordancewith the present invention may be coupled to the system controller.Instructions for implementing appropriate control operations areexecuted on the processor. These instructions may be stored on thememory devices associated with the controller or they may be providedover a network. In certain embodiments, the system controller executessystem control software . . . .

System control software may be configured in any suitable way. Forexample, various process tool component subroutines or control objectsmay be written to control operation of the process tool componentsnecessary to carry out various process tool processes. System controlsoftware may be coded in any suitable computer readable programminglanguage.

In some embodiments, system control software includes input/outputcontrol (IOC) sequencing instructions for controlling the variousparameters described above. For example, each phase of an electroplatingprocess may include one or more instructions for execution by the systemcontroller. The instructions for setting process conditions for animmersion process phase may be included in a corresponding immersionrecipe phase. In some embodiments, the electroplating recipe phases maybe sequentially arranged, so that all instructions for an electroplatingprocess phase are executed concurrently with that process phase.

Other computer software and/or programs may be employed in someembodiments. Examples of programs or sections of programs for thispurpose include a substrate positioning program, an electrolytecomposition control program, a pressure control program, a heatercontrol program, and a potential/current power supply control program.

In some cases, the controllers control one or more of the followingfunctions: wafer immersion (translation, tilt, rotation), fluid transferbetween tanks, etc. The wafer immersion may be controlled by, forexample, directing the wafer lift assembly, wafer tilt assembly andwafer rotation assembly to move as desired. The controller may controlthe fluid transfer between tanks by, for example, directing certainvalves to be opened or closed and certain pumps to turn on and off. Thecontrollers may control these aspects based on sensor output (e.g., whencurrent, current density, potential, pressure, etc. reach a certainthreshold), the timing of an operation (e.g., opening valves at certaintimes in a process) or based on received instructions from a user.

The apparatus/process described hereinabove may be used in conjunctionwith lithographic patterning tools or processes, for example, for thefabrication or manufacture of semiconductor devices, displays, LEDs,photovoltaic panels and the like. Typically, though not necessarily,such tools/processes will be used or conducted together in a commonfabrication facility. Lithographic patterning of a film typicallycomprises some or all of the following steps, each step enabled with anumber of possible tools: (1) application of photoresist on a workpiece,i.e., substrate, using a spin-on or spray-on tool; (2) curing ofphotoresist using a hot plate or furnace or UV curing tool; (3) exposingthe photoresist to visible or UV or x-ray light with a tool such as awafer stepper; (4) developing the resist so as to selectively removeresist and thereby pattern it using a tool such as a wet bench; (5)transferring the resist pattern into an underlying film or workpiece byusing a dry or plasma-assisted etching tool; and (6) removing the resistusing a tool such as an RF or microwave plasma resist stripper.

Features of a Channeled Ionically Resistive Element Electrical Function

In certain embodiments, the channeled ionically resistive element 206approximates a nearly constant and uniform current source in theproximity of the substrate (cathode) and, as such, may be referred to asa high resistance virtual anode (HRVA) in some contexts. Normally, theCIRP 206 is placed in close proximity with respect to the wafer. Incontrast, an anode in the same close-proximity to the substrate would besignificantly less apt to supply a nearly constant current to the wafer,but would merely support a constant potential plane at the anode metalsurface, thereby allowing the current to be greatest where the netresistance from the anode plane to the terminus (e.g., to peripheralcontact points on the wafer) is smaller. So while the channeledionically resistive element 206 has been referred to as ahigh-resistance virtual anode (HRVA), this does not imply thatelectrochemically the two are interchangeable. Under the bestoperational conditions, the CIRP 206 would more closely approximate andperhaps be better described as a virtual uniform current source, withnearly constant current being sourced from across the upper plane of theCIRP 206. While the HRVA is certainly viewable as a “virtual currentsource”, i.e. it is a plane from which the current is emanating, andtherefore can be considered a “virtual anode” because it can be viewedas a location or source from which anodic current emanates, it is therelatively high-ionic-resistance of the CIRP 206 (with respect to theelectrolyte) that leads the nearly uniform current across its face andto further advantageous, generally superior wafer uniformity whencompared to having a metallic anode located at the same physicallocation. The plate's resistance to ionic current flow increases withincreasing specific resistance of electrolyte contained within thevarious channels of the plate 206 (often but not always having the sameor nearly similar resistance of the catholyte), increased platethickness, and reduced porosity (less fractional cross sectional areafor current passage, for example, by having fewer holes of the samediameter, or the same number of holes with smaller diameters, etc.).

Structure

The CIRP 206 contains micro size (typically less than 0.04″)through-holes that are spatially and ionically isolated from each otherand do not form interconnecting channels within the body of CIRP, inmany but not all implementations. Such through-holes are often referredto as non-communicating through-holes. They typically extend in onedimension, often, but not necessarily, normal to the plated surface ofthe wafer (in some embodiments the non-communicating holes are at anangle with respect to the wafer which is generally parallel to the CIRPfront surface). Often the through-holes are parallel to one another.Often the holes are arranged in a square array. Other times the layoutis in an offset spiral pattern. These through-holes are distinct from3-D porous networks, where the channels extend in three dimensions andform interconnecting pore structures, because the through-holesrestructure both ionic current flow and fluid flow parallel to thesurface therein, and straighten the path of both current and fluid flowtowards the wafer surface. However, in certain embodiments, such aporous plate, having an interconnected network of pores, may be used inplace of the 1-D channeled element (CIRP). When the distance from theplate's top surface to the wafer is small (e.g., a gap of about 1/10 thesize of the wafer radius, for example less than about 5 mm), divergenceof both current flow and fluid flow is locally restricted, imparted andaligned with the CIRP channels.

One example CIRP 206 is a disc made of a solid, non-porous dielectricmaterial that is ionically and electrically resistive. The material isalso chemically stable in the plating solution of use. In certain casesthe CIRP 206 is made of a ceramic material (e.g., aluminum oxide,stannic oxide, titanium oxide, or mixtures of metal oxides) or a plasticmaterial (e.g., polyethylene, polypropylene, polyvinylidene difluoride(PVDF), polytetrafluoroethylene, polysulphone, polyvinyl chloride (PVC),polycarbonate, and the like), having between about 6,000-12,000non-communicating through-holes. The disc 206, in many embodiments, issubstantially coextensive with the wafer (e.g., the CIRP disc 206 has adiameter of about 300 mm when used with a 300 mm wafer) and resides inclose proximity to the wafer, e.g., just below the wafer in awafer-facing-down electroplating apparatus. Preferably, the platedsurface of the wafer resides within about 10 mm, more preferably withinabout 5 mm of the closest CIRP surface. To this end, the top surface ofthe channeled ionically resistive plate 206 may be flat or substantiallyflat. Often, both the top and bottom surfaces of the channeled ionicallyresistive plate 206 are flat or substantially flat.

Another feature of the CIRP 206 is the diameter or principal dimensionof the through-holes and its relation to the distance between the CIRP206 and the substrate. In certain embodiments, the diameter of eachthrough-hole (or of a majority of through-holes, or the average diameterof the through-holes) is no more than about the distance from the platedwafer surface to the closest surface of the CIRP 206. Thus, in suchembodiments, the diameter or principal dimension of the through holesshould not exceed about 5 mm, when the CIRP 206 is placed within about 5mm of the plated wafer surface.

As above, the overall ionic and flow resistance of the plate 206 isdependent on the thickness of the plate and both the overall porosity(fraction of area available for flow through the plate) and thesize/diameter of the holes. Plates of lower porosities will have higherimpinging flow velocities and ionic resistances. Comparing plates of thesame porosity, one having smaller diameter 1-D holes (and therefore alarger number of 1-D holes) will have a more micro-uniform distributionof current on the wafer because there are more individual currentsources, which act more as point sources that can spread over the samegap, and will also have a higher total pressure drop (high viscous flowresistance).

In certain cases, however, the ionically resistive plate 206 is porous,as mentioned above. The pores in the plate 206 may not form independent1-D channels, but may instead form a mesh of through holes which may ormay not interconnect. It should be understood that as used herein, theterms channeled ionically resistive plate and channeled ionicallyresistive element (CIRP) are intended to include this embodiment, unlessotherwise noted.

Vertical Flow Through the Through-Holes

The presence of an ionically resistive but ionically permeable element(CIRP) 206 close to the wafer substantially reduces the terminal effectand improves radial plating uniformity in certain applications whereterminal effects are operative/relevant, such as when the resistance ofelectrical current in the wafer seed layer is large relative to that inthe catholyte of the cell. The CIRP 206 also simultaneously provides theability to have a substantially spatially-uniform impinging flow ofelectrolyte directed upwards at the wafer surface by acting as a flowdiffusing manifold plate. Importantly, if the same element 206 is placedfarther from the wafer, the uniformity of ionic current and flowimprovements become significantly less pronounced or non-existent.

Further, because non-communicating through-holes do not allow forlateral movement of ionic current or fluid motion within the CIRP, thecenter-to-edge current and flow movements are blocked within the CIRP206, leading to further improvement in radial plating uniformity. In theembodiment shown in FIG. 9, the CIRP 206 is a perforated plate havingapproximately 9000 uniformly spaced one-dimensional holes acting asmicrochannels and arranged in a square array (i.e., the holes arearranged in columns and rows) over the face of the plate (e.g., over asubstantially circular area having a diameter of about 300 mm in thecase of plating a 300 mm wafer) and with an effective average porosityof about 4.5%, and an individual microchannel hole size of about 0.67 mm(0.026 inches) in diameter. Also shown in FIG. 9 are the flowdistribution adjustment rods 270, which may be used to preferentiallydirect flow to enter the cross flow manifold 226 either through the CIRPmanifold 208 and up through the holes in the CIRP 206, or in through thecross flow injection manifold 222 and cross flow showerhead 242. Thecross flow confinement ring 210 is fitted on top of the CIRP, which issupported by the membrane frame 274.

It is noted that in some embodiments, the CIRP plate 206 can be usedprimarily or exclusively as an intra-cell electrolyte flow resistive,flow controlling and thereby flow shaping element, sometimes referred toas a turboplate. This designation may be used regardless of whether ornot the plate 206 tailors radial deposition uniformity by, for example,balancing terminal effects and/or modulating the electric field orkinetic resistances of plating additives coupled with the flow withinthe cell. Thus, for example, in TSV and WLP electroplating, where theseed metal thickness is generally large (e.g. >1000 Å thick) and metalis being deposited at very high rates, uniform distribution ofelectrolyte flow is very important, while radial non-uniformity controlarising from ohmic voltage drop within the wafer seed may be lessnecessary to compensate for (at least in part because the center-to-edgenon-uniformities are less severe where thicker seed layers are used).Therefore the CIRP plate 206 can be referred to as both an ionicallyresistive ionically permeable element, and as a flow shaping element,and can serve a deposition-rate corrective function by either alteringthe flow of ionic current, altering the convective flow of material, orboth.

Distance Between Wafer and Channeled Plate

In certain embodiments, a wafer holder 254 and associated positioningmechanism hold a rotating wafer very close to the parallel upper surfaceof the channeled ionically resistive element 206. During plating, thesubstrate is generally positioned such that it is parallel orsubstantially parallel to the ionically resistive element (e.g., withinabout 10°). Though the substrate may have certain features thereon, onlythe generally planar shape of the substrate is considered in determiningwhether the substrate and ionically resistive element are substantiallyparallel.

In typical cases, the separation distance is about 1-10 millimeters, orabout 2-8 millimeters. This small plate to wafer distance can create aplating pattern on the wafer associated with proximity “imaging” ofindividual holes of the pattern, particularly near the center of waferrotation. In such circumstances, a pattern of plating rings (inthickness or plated texture) may result near the wafer center. To avoidthis phenomenon, in some embodiments, the individual holes in the CIRP206 (particularly at and near the wafer center) can be constructed tohave a particularly small size, for example less than about ⅕^(th) theplate to wafer gap. When coupled with wafer rotation, the small poresize allows for time averaging of the flow velocity of impinging fluidcoming up as a jet from the plate 206 and reduces or avoids small scalenon-uniformities (e.g., those on the order of micrometers). Despite theabove precaution, and depending on the properties of the plating bathused (e.g. particular metal deposited, conductivities, and bathadditives employed), in some cases deposition may be prone to occur in amicro-non-uniform pattern (e.g., forming center rings) as the timeaverage exposure and proximity-imaging-pattern of varying thickness (forexample, in the shape of a “bulls eye” around the wafer center) andcorresponding to the individual hole pattern used. This can occur if thefinite hole pattern creates an impinging flow pattern that isnon-uniform and influences the deposition. In this case, introducinglateral flow across the wafer center, and/or modifying the regularpattern of holes right at and/or near the center, have both been foundto largely eliminate any sign of micro-non-uniformities otherwise foundthere.

Porosity of Channeled Plate

In various embodiments, the channeled ionically resistive plate 206 hasa sufficiently low porosity and pore size to provide a viscous flowresistance backpressure and high vertical impinging flow rates at normaloperating volumetric flow rates. In some cases, about 1-10% of thechanneled ionically resistive plate 206 is open area allowing fluid toreach the wafer surface. In particular embodiments, about 2-5% the plate206 is open area. In a specific example, the open area of the plate 206is about 3.2% and the effective total open cross sectional area is about23 cm².

Hole Size of Channeled Plate

The porosity of the channeled ionically resistive plate 206 can beimplemented in many different ways. In various embodiments, it isimplemented with many vertical holes of small diameter. In some casesthe plate 206 does not consist of individual “drilled” holes, but iscreated by a sintered plate of continuously porous material. Examples ofsuch sintered plates are described in U.S. Pat. No. 6,964,792, [attorneydocket NOVLP023] which is herein incorporated by reference in itsentirety. In some embodiments, drilled non-communicating holes have adiameter of about 0.01 to 0.05 inches. In some cases, the holes have adiameter of about 0.02 to 0.03 inches. As mentioned above, in variousembodiments the holes have a diameter that is at most about 0.2 timesthe gap distance between the channeled ionically resistive plate 206 andthe wafer. The holes are generally circular in cross section, but neednot be. Further, to ease construction, all holes in the plate 206 mayhave the same diameter. However this need not be the case, and both theindividual size and local density of holes may vary over the platesurface as specific requirements may dictate.

As an example, a solid plate 206 made of a suitable ceramic or plasticmaterial (generally a dielectric insulating and mechanically robustmaterial), having a large number of small holes provided therein, e.g.at least about 1000 or at least about 3000 or at least about 5000 or atleast about 6000 (9465 holes of 0.026 inches diameter has been founduseful). As mentioned, some designs have about 9000 holes. The porosityof the plate 206 is typically less than about 5 percent so that thetotal flow rate necessary to create a high impinging velocity is not toogreat. Using smaller holes helps to create a large pressure drop acrossthe plate as compared to larger holes, aiding in creating a more uniformupward velocity through the plate.

Generally, the distribution of holes over the channeled ionicallyresistive plate 206 is of uniform density and non-random. In some cases,however, the density of holes may vary, particularly in the radialdirection. In a specific embodiment, as described more fully below,there is a greater density and/or diameter of holes in the region of theplate that directs flow toward the center of the rotating substrate.Further, in some embodiments, the holes directing electrolyte at or nearthe center of the rotating wafer may induce flow at a non-right anglewith respect to the wafer surface. Further, the hole patterns in thisregion may have a random or partially random distribution of non-uniformplating “rings” to address possible interaction between a limited numberof holes and the wafer rotation. In some embodiments, the hole densityproximate an open segment of a flow diverter or confinement ring 210 islower than on regions of the channeled ionically resistive plate 206that are farther from the open segment of the attached flow diverter orconfinement ring 210.

It is to be understood that the configurations and/or approachesdescribed herein are exemplary in nature, and that these specificembodiments or examples are not to be considered in a limiting sense,because numerous variations are possible. The specific routines ormethods described herein may represent one or more of any number ofprocessing strategies. As such, various acts illustrated may beperformed in the sequence illustrated, in other sequences, in parallel,or in some cases omitted. Likewise, the order of the above describedprocesses may be changed.

The subject matter of the present disclosure includes all novel andnonobvious combinations and sub-combinations of the various processes,systems and configurations, and other features, functions, acts, and/orproperties disclosed herein, as well as any and all equivalents thereof.

Examples and Experimental

A few observations that suggest that improved cross flow through thecross flow manifold 226 is desirable are presented in this section.Throughout this section, two basic plating cell designs are tested. Bothdesigns contain a confinement ring 210, sometimes referred to as a flowdiverter, defining a cross flow manifold 226 on top of the channeledionically resistive plate 206. The first design, sometimes referred toas the control design and/or the TC1 design, does not include a sideinlet to this cross flow manifold 226. Instead, in the control design,all flow into the cross flow manifold 226 originates below the CIRP 206and travels up through the holes in the CIRP 206 before impinging on thewafer and flowing across the face of the substrate. The second design,sometimes referred to as the current design and/or the TC2 design,includes a cross flow injection manifold 222 and all associated hardwarefor injecting fluid directly into the cross flow manifold 226 withoutpassing through the channels or pores in the CIRP 206 (note that in somecases, however, the flow delivered to the cross flow injection manifoldpasses through dedicated channels near the periphery of the CIRP 206,such channels being distinct/separate from the channels used to directfluid from the CIRP manifold 208 to the cross flow manifold 226).

Thickness Distribution Non Uniformity.

When utilizing previous plating cell designs that lack a cross flowinjection manifold, flow conditions often arise such that in certainregions of the wafer (e.g., a region near (but typically offset from)the center of the wafer) the vertical fluid jetting velocity dominatesover the horizontal cross flow velocity. In such cases, the individualjets are amplified and result in a non-uniform thickness distribution.FIG. 10 shows a graph of film thickness vs. position on the wafer for asubstrate plated with copper in a control plating cell lacking a sideinlet to the cross flow manifold. As seen in FIG. 10, the film wasthicker towards the edge of the substrate and thinner towards the centerof the substrate. This radial thickness difference is not optimal.

FIG. 11 shows a graph of film thickness vs. position on the wafer fortwo substrates: one substrate plated in a control design plating cell(shown with round dots and designated here as TC1), and one substrateplated in a current design plating cell having a cross flow injectionmanifold 222 (shown with triangles and designated here as TC2). The datawas generated by blanket deposition of copper on a wafer with platingchemistry that employed a leveler. FIG. 11 shows that wafer centernon-uniformity (or ringing) is observed in the control apparatus, but isdramatically improved when using the current apparatus (with a sideinlet to the cross flow manifold).

Feature Shape Variation.

The fundamental cross flow imbalance between the azimuthally oppositepositions on a wafer plated in a control apparatus having an outlet 234at one azimuthal location, but no inlet 250 at an opposite azimuthalposition in a cross flow manifold 226, results in non-uniformwithin-feature convection. The net result is a bump shape which showssome thickness non uniformity (e.g., tilt in one direction).

FIG. 12 shows the within-feature shape of various microbumps located atdifferent positions on a substrate for microbumps plated in a controldesign plating cell (upper panels, designated as TC1) and for microbumpsplated in a current design plating cell according to various embodimentsherein (lower panels, designated as TC2). For each graph in FIG. 12, thex-axis corresponds to the position on the wafer, as indicated by thelarge arrows at the top of the figure, and the y-axis corresponds to theheight of the given microbump at that position. Thus, each graph showsthe outline shape of the microbump plated at a particular location onthe substrate.

For context, the “bottom” region of the wafer is where a notch on thewafer exists.

The “top” of the wafer is the side of the wafer opposite that of wherethe notch occurs. The four smaller arrows in the upper panels of FIG. 12correspond to the tilt of the plated feature (i.e., the arrow pointstowards the taller side of the feature). Ideally, these arrows would behorizontal, meaning that there is no tilt to the feature. It should benoted that due to the rotation of the substrate during plating, there isa center-to-edge component of the electrolyte flow pattern. The smallarrows in the upper panels of FIG. 12 point in the direction oppositethis flow.

In generating the data shown in FIG. 12, copper bumps were deposited in20×20 μm features in photoresist. For the control design, the cross flowreached its maximum velocity, and convection driven mass transferdominated, at the outlet 234 of the cross flow manifold 226. As aconsequence, the inner “upstream” sides of the bumps experienced greaterdeposition rates, as illustrated in the data profiles shown in the upperpanels of FIG. 12. A notable improvement is observed in the bumpprofiles generated using forced cross flow in accordance with theembodiments disclosed herein, as shown in the lower panels of FIG. 12.Overall, FIG. 12 shows that there was very little feature tilt for thecurrent design as compared to the control design.

Silver Composition Non Uniformity.

A control apparatus with no side inlet to the cross flow manifoldresults in significantly less cross flow over certain areas of the wafersurface as compared to other areas of the wafer surface. When using suchan apparatus to plate an alloy, the composition of the alloy may not beuniform across the face of the wafer. For example, when using such anapparatus to plate tin-silver solder bumps, the concentration of silvermay be lower near the center of the wafer and higher near the edges ofthe wafer. This non-uniform alloy composition highlights the non-uniformcross flow pattern of the plating solution. FIG. 13 shows the silvercomposition vs. on wafer position for tin-silver bumps plated in acontrol design plating cell. The x-axis represents the position of thebump on the wafer, while the y-axis represents the percentage of silverin the bump. Notably, the percentage of silver is lower for bumps platedat/near the center, as compared to bumps plated closer to the edge ofthe wafer. In the case of SnAg solder plating, silver is a diffusionlimited species. The uniform composition of the SnAg plated material isa parameter in maintaining good solder welds. The composition uniformityof the SnAg plated material may be improved by enhancing the diffusionof species in the system, for example by introducing cross flow from aside inlet 250 according to the embodiments herein.

FIGS. 14A-B through FIGS. 18A-B compare the flow patterns achieved usingthe control plating cell (14A, 15A, 16A, 17A and 18A) vs. the currentplating cell having a side inlet to the cross flow manifold (14B, 15B,16B, 17B and 18B). The results were generated using numerical models ofthe cross flow manifold.

FIG. 14A shows a top-down view of part of a control design platingapparatus. Specifically, the figure shows a CIRP 206 with a flowdiverter 210. FIG. 14B shows a top-down view of part of a current designplating apparatus, specifically showing the CIRP 206, flow diverter 210and cross flow injection manifold 222/cross flow manifold inlet250/cross flow showerhead 242. The direction of flow in FIGS. 14A-B isgenerally left to right, towards the outlet 234 on the flow diverter210. The designs shown in FIGS. 14A-B correspond to the designs modeledin FIGS. 15A-B through 17A-B.

FIG. 15A shows the flow through the cross flow manifold 226 for thecontrol design. In this case, all the flow in the cross flow manifold226 originates from below the CIRP 206. The magnitude of the flow at aparticular point is indicated by the size of the arrows. In the controldesign of FIG. 15A, the magnitude of the flow increases substantiallythroughout the cross flow manifold 226 as additional fluid passesthrough the CIRP 206, impinges upon the wafer, and joins the cross flow.In the current design of FIG. 15B, however, this increase in flow ismuch less substantial. The increase is not as great because a certainamount of fluid is delivered directly into the cross flow manifold 226through the cross flow injection manifold 222 and associated hardware.

FIG. 16A shows the flow velocity across the face of the wafer in thecontrol design depicted in FIG. 14A. The flow is much faster (depictedby the darker shades) near the outlet 234 of the flow diverter, and muchslower (depicted by the lighter shades) on the side opposite the exit.In contrast, FIG. 16B shows that the flow velocity is much more uniformin the case of the current design depicted in FIG. 14B.

FIG. 17A depicts the horizontal velocity across the face of a substrateplated in the control design apparatus shown in FIG. 14A. Notably, theflow velocity starts at zero (at the position opposite the flow diverteroutlet) and increases until reaching the outlet 234. Unfortunately, theaverage flow at the center of the wafer is relatively low in the controlembodiments. As a consequence, the jets of catholyte emitted from thechannels of the channeled ionically resistive plate 206 predominatehydrodynamically in the center region. The problem is not as pronouncedtowards the edge regions of the work piece because the rotation of thewafer creates an azimuthally averaged cross flow experience.

FIG. 17B depicts the horizontal velocity across the face of a substrateplated in the current design shown in FIG. 14B. In this case, thehorizontal velocity starts at the inlet 250 at a non-zero value due tothe fluid injected from the cross flow injection manifold 222, throughthe side inlet 250 and into the cross flow manifold 226. Further, theflow rate at the center of the wafer is increased in the current design,as compared to the control design, thereby reducing or eliminating theregion of low cross flow near the center of the wafer where theimpinging jets may otherwise dominate. Thus, the side inletsubstantially improves the uniformity of cross flow rates along theinlet-to-outlet direction, and will result in more uniform platingthickness.

FIG. 18A shows modeling results indicating the cross flow velocity(z-velocity) for a specific control design case where 12 L/min totalflow is delivered to the cross flow manifold 226 (all fluid entering thecross flow manifold through the CIRP holes). The cross flow velocity isvery non-uniform, as indicated by the many shades of gray/black presentin the figure. The flow velocity is lowest near the center of the waferand towards the side of the wafer opposite the inlet. The flow ishighest near the outlet 234. FIG. 18B shows similar modeling resultsindicating the cross flow velocity for a specific case utilizing thecurrent design with a side inlet 250, where 3 L/min plating fluid isdelivered through the holes in the CIRP 206, and 9 L/min plating fluidis delivered directly through the cross flow injection manifold/sideinlet 222/250. FIG. 18B shows the very significant improvement in crossflow velocity uniformity that may be achieved using a side inlet 250 forthe cross flow manifold 226. Although the flow velocity is slightlyhigher near the edges of the wafer than near the center of the wafer,this difference is slight compared to the differences seen in thecontrol design in FIG. 18A.

A number of concept and feasibility tests were carried out with hardwareimplementing the embodiments disclosed herein.

FIGS. 19A-B show the results of static imprint tests comparing thecontrol (no side inlet) and current (side inlet 250) embodiments. Eachtest consisted of a 5 minute etch of a 1000 Å copper seed wafer whilethe plating cup 254 was positioned at a plating position with norotation. In the case of the control design, as shown in FIG. 19A, theetch pattern shows a very distinct cross hatched pattern, whichindicates a region of jetted flow (nil cross flow). As explained above,these regions where the jetted flow dominates over the cross flow areundesirable in terms of plating uniformity. These regions may sometimesbe referred to as “dead spots.” The static imprint pattern for currentembodiment did not reveal any such pattern, as shown in FIG. 19B. Thecurrent embodiment with the side inlet 250 also resulted in an area nearthe inlet 250 where etching was higher (indicated by the darker areatowards the left side of the substrate in FIG. 19B), which correlates toan area of turbulent flow.

As mentioned above, in some embodiments, the adjustment of the fluidicadjustment rods 270 allows the operator or controller of theelectroplating cell to favor flow to the cross flow injection manifold222 or to the channeled ionically resistive plate manifold 208.

FIG. 20 provides data generated by controlling catholyte flow to theCIRP 206 and cross flow manifolds 226 with the various fluidicadjustment rods 270 in a cell having control rods 270 in each of 12feeder channels: 6 for the cross flow injection manifold 258 and 6 forthe CIRP manifold 262. Each curve in the FIG. 48, 47, etc.) refers tothe fluidic adjustment rod 270 diameter in mm. The 48 mm rod wasessentially a fully restricting rod while the 32 mm rod was the leastrestricting rod used in this study (besides the fully open state whichis noted as 00). In addition, each curve was generated by installing sixrods 270 of the same size in either the cross flow injection manifoldfeeders 258 or CIRP manifold feeders 262. Furthermore, when the fluidicadjustment rods 270 were installed on the cross flow manifold feeders258, no fluidic adjustment rods were installed on the CIRP manifoldfeeders 262, and vice versa. The data shows that by using various sizedcontrol rods 270, from which various pressures and flow rates weremeasured, one can modify the flows from side to side and across thevarious 12 feeder channels 258 and 262.

FIGS. 21A-B provide modeling data showing the impinging flow velocity(y-velocity) at different points near the wafer for the two confinementring 210 setups shown in FIGS. 8A-B, respectively. The velocity ismodeled at a plane 1 mm below the wafer plane. In relation to FIGS.21A-B, the cross flow is in the −z direction (top to bottom asdepicted). However, the velocity being modeled in this figure is they-velocity, which is the flow velocity in the direction normal to theCIRP 206, pointing towards the wafer. Flow moving upwards towards thewafer has a positive y-velocity. For the preliminary current designshown in FIG. 8A, where the inlet 250 to the cross flow manifold 226terminates under the wafer, the flow coming out of the inlet 250 isinitially relatively non-uniform, as shown in FIG. 21A. In contrast, forthe revised current design shown in FIG. 8B, where the inlet 250 to thecross flow manifold 226 terminates further radially outward (under thecup 254 instead of under the wafer), the flow emanating from the inlet250 is substantially more uniform. The location where the inlet 250 tothe cross flow manifold 226 terminates corresponds to the location wherethe cross flow confinement ring 210 terminates, in many cases. FIG. 21Cshows modeling data illustrating the flow path near the edge of thesubstrate in the case of the initial design shown in FIG. 8A and modeledin FIG. 21A. It is believed that this flow, which bends upwards andbackwards near the inlet, corresponds to the non-uniformities seen nearthe inlet in FIG. 21A.

FIGS. 22A-B illustrate the effect of the angular distribution of crossflow showerhead holes 246 on cross flow uniformity. For both cases, theflow directional fins 266 were positioned in an angularly uniformmanner, the cross flow was in the z direction (from the bottom to thetop of the page), and the velocity was modeled at a plane 0.2 mm belowthe wafer plane. Further, for each case, the flow was modeled with 12L/min total flow, with 9 L/min equally distributed across 139 cross flowshowerhead holes 246, and 3 L/min delivered to the CIRP manifold 208.

FIG. 22A depicts the modeled cross flow velocity where the separationsbetween adjacent cross flow showerhead holes 246 are angularly uniform.In this case, the length of the arc between each pair of adjacentshowerhead holes 246 is the same. However, the spacing between each pairof holes 246 is non-uniform in the x-direction (the directionperpendicular to the direction of cross flow), because adjacent holesnear the center of the inlet will be farther apart compared to adjacentholes near the outer edges of the inlet. This x-direction non-uniformityarises simply due to the projection of angularly uniform holes onto alinear axis. Because the holes 246 near the center of the inlet arefarther apart, the cross flow across the center of the electroplatingapparatus will be somewhat lower than the cross flow near the edges.

FIG. 22B depicts the modeled cross flow velocity where the separationbetween adjacent cross flow showerhead holes 246 are not angularlyuniform. As compared to the case shown in FIG. 22A, there are moreshowerhead holes 246 clustered near the center of the inlet 250, andfewer showerhead holes 246 towards the edges of the inlet 250. Thisresults in more uniform separation between adjacent holes 246, asmeasured in the x-direction (but less uniform separation as measured bythe arcs between adjacent holes 246). Because the cross flow originatesfrom these showerhead holes 246 and moves in the z-direction,perpendicular to the x-direction, the uniform spacing of the holes 246in the x-direction can result in more uniform cross flow velocitiesacross the face of the wafer. Importantly, as compared to the case shownin FIG. 22A, the flow pattern in FIG. 22B is more uniform, and thevelocity differences between the center and the edges of the apparatusare minimized.

Other Embodiments

While the above is a full description of the specific embodiments,various modifications, alternative constructions and equivalents may beused. Therefore, the above description and illustrations should not betaken as limiting the scope of the present invention which is defined bythe appended claims.

What is claimed is:
 1. An electroplating apparatus comprising: (a) anelectroplating chamber configured to contain an electrolyte and an anodewhile electroplating metal onto a substantially planar substrate; (b) asubstrate holder configured to hold a substantially planar substratesuch that a plating face of the substrate is separated from the anodeduring electroplating; (c) an ionically resistive element including asubstrate-facing surface that is separated from the plating face of thesubstrate by a gap of about 10 mm or less, wherein the ionicallyresistive element is at least coextensive with the plating face of thesubstrate during electroplating, the ionically resistive element adaptedto provide ionic transport through the element during electroplating;(d) an inlet to the gap for introducing electrolyte to the gap; and (e)an outlet to the gap for receiving electrolyte flowing in the gap,wherein the inlet and outlet are positioned proximate azimuthallyopposing perimeter locations on the plating face of the substrate duringelectroplating, and wherein the inlet and outlet are adapted to generatecross-flowing electrolyte in the gap to create or maintain a shearingforce on the plating face of the substrate during electroplating.
 2. Theelectroplating apparatus of claim 1, wherein the ionically resistiveelement has a porosity of between about 1-10%.
 3. The electroplatingapparatus of claim 2, wherein the ionically resistive element comprisesat least 1000 paths through which electrolyte may flow duringelectroplating.
 4. The electroplating apparatus of claim 3, wherein atleast some of the paths are configured to deliver electrolyte towardsthe substrate at a velocity of at least about 10 cm/s at an outlet ofthe at least some paths.
 5. The electroplating apparatus of claim 1,wherein the ionically resistive element is configured to shape anelectric field and control electrolyte flow characteristics proximatethe substrate during electroplating.
 6. The electroplating apparatus ofclaim 1, further comprising a lower manifold region positioned below alower face of the ionically resistive element, wherein the lower facefaces away from the substrate holder.
 7. The electroplating apparatus ofclaim 6, further comprising a central electrolyte chamber and one ormore feed channels configured to deliver electrolyte from the centralelectrolyte chamber to both the inlet and to the lower manifold region.8. The electroplating apparatus of claim 7, further comprising a pumpfor delivering electrolyte to or from the central electrolyte chamber.9. The electroplating apparatus of claim 8, wherein the pump and theinlet are adapted to deliver electrolyte in the gap at a cross flowvelocity of at least about 3 cm/s across a center point on the platingface of the substrate.
 10. The electroplating apparatus of claim 1,further comprising a cross flow injection manifold fluidically coupledto the inlet.
 11. The electroplating apparatus of claim 10, wherein thecross flow injection manifold is at least partially defined by a cavityin the ionically resistive element.
 12. The electroplating apparatus ofclaim 1, further comprising flow directing elements positioned in thegap, wherein the flow directing elements are adapted to causeelectrolyte to flow in a substantially linear flow path from the inletto the outlet.
 13. The electroplating apparatus of claim 12, wherein theflow directing elements are partitions located downstream from the inletand configured to divide flowing electrolyte into adjacent streams inthe gap.
 14. The electroplating apparatus of claim 1, further comprisinga flow confinement ring positioned over a peripheral portion of theionically resistive element.
 15. The electroplating apparatus of claim14, further comprising a gasket positioned between the ionicallyresistive element and the flow confinement ring.
 16. The electroplatingapparatus of claim 1, further comprising a membrane frame for supportinga membrane, wherein the membrane separates the electroplating chamberinto a cathode chamber and an anode chamber.
 17. The electroplatingapparatus of claim 1, further comprising a weir wall positioned radiallyoutside the gap and configured to receive electrolyte flowing throughthe outlet.
 18. The electroplating apparatus of claim 1, furthercomprising a mechanism for rotating the substrate holder during plating.19. The electroplating apparatus of claim 1, wherein the ionicallyresistive element is positioned substantially parallel to the substrateduring electroplating.
 20. The electroplating apparatus of claim 1,wherein the inlet spans an arc between about 90-180° proximate theperimeter of the plating face of the substrate.
 21. The electroplatingapparatus of claim 1, wherein the inlet is separated into a plurality ofazimuthally distinct and fluidically separated segments.
 22. Theelectroplating apparatus of claim 21, further comprising a plurality ofelectrolyte feed inlets configured to deliver electrolyte to theazimuthally distinct segments of the inlet.
 23. The electroplatingapparatus of claim 22, further comprising one or more flow controlelements configured to independently control a plurality of volumetricflow rates of electrolyte in the plurality of electrolyte feed inletsduring electroplating.
 24. A method for electroplating a substratecomprising: (a) receiving a substantially planar substrate in asubstrate holder, wherein a plating face of the substrate is exposed,and wherein the substrate holder is configured to hold the substratesuch that the plating face of the substrate is separated from the anodeduring electroplating; (b) immersing the substrate in electrolyte,wherein a gap of about 10 mm or less is formed between the plating faceof the substrate and an upper surface of an ionically resistive element,wherein the ionically resistive element is at least coextensive with theplating face of the substrate, and wherein the ionically resistiveelement is adapted to provide ionic transport through the ionicallyresistive element during electroplating; (c) flowing electrolyte incontact with the substrate in the substrate holder (i) from a sideinlet, into the gap, and out a side outlet, and (ii) from below theionically resistive element, through the ionically resistive element,into the gap, and out the side outlet, wherein the inlet and outlet arepositioned proximate azimuthally opposed perimeter locations on theplating face of the substrate, and wherein the inlet and outlet aredesigned or configured to generate cross-flowing electrolyte in the gapduring electroplating; (d) rotating the substrate holder; and (e)electroplating material onto the plating face of the substrate whileflowing the electrolyte as in (c).
 25. The method of claim 24, whereinflowing electrolyte in operation (c) comprises flowing electrolyte at across flow velocity of at least about 3 cm/s across a center point onthe plating face of the substrate.
 26. The method of claim 24, whereinduring operation (c), electrolyte exits the ionically resistive elementat a velocity of at least about 10 cm/s.
 27. The method of claim 24,wherein the side inlet is separated into two or more azimuthallydistinct and fluidically separated sections, and wherein the flow ofelectrolyte to the azimuthally distinct sections of the inlet areindependently controlled.
 28. The method of claim 24, wherein the sideoutlet is separated into two or more azimuthally distinct side outletsections.
 29. The method of claim 28, further comprising flowingelectrolyte at different flow rates through at least two of theazimuthally distinct outlet sections.
 30. The method of claim 24,wherein flow directing elements are positioned in the gap, and whereinthe flow directing elements cause electrolyte to flow in a substantiallylinear flow path from the side inlet to the side outlet.